after several years of clj-study, i believe time has come now for me to venture into something new. 
looking back on my clj-experience, i have to say, that it was a great ride. i feel like i was able to learn about a great many new and interesting things and ideas, which allowed me to grow in a number of dimensions.
also, i am grateful for all the help that i have received from the clj-community.
anyway, best of luck to everyone; stay safe! and:
頑張って
Good luck in your future endeavors! Do you know what tech you are most likely to go after next?
Thank you. Actually i have decided that i would like to invest some more time in learning about mathematics. 
Ah, as a fellow mathematician by trade, I salute you for that!
@taf all the best wishes!
Re: mathematics
You may like to know that Clojure is becoming a fantastic way to learn (some parts of) math. Sicmutils, together with the various tools and libraries for data visualizations, and together with the REPL, is becoming an amazing way to access ideas, check them, and make them clear. This applies to very concrete examples, but also to more abstract ideas.
There is a study group about all that, that just started. Some really nice people of various backgrounds are helping each other to grasp some of the concepts of calculus, symbolic math, geometry, mechanics, etc.
As someone who’s learned math in more conventional ways, I feel that this way of REPL-driven math opens up wonderful ways to learn and understand things. It could have mattered a lot if I had it with me as a student.
Maybe you’d like to consider joining that study group, alongside your path with math. I’ll be happy to chat about this and see if I can help. 
Thank you so much for your kind words!
Now about the mathematics 
… here is the thing… i just worked my way through a good deal of the following book, which i absolutely loved!
I guess it is actually intended not even for university students but for high school students who are about to enter university. still some of the problems in the book, i was not able to solve… for the life of me… really
for example consider the following ( i hope it is OK for me to post this short excerpt from the book here,… also plz ignore my silly coloring of everything… )
so… basically i get that this stuff is just absolutely beautiful… i am just not any good at it!
anyway… i am just starting out… and so i want to simply tackle a number of books on my own for the time being… but i really really do appreciate your offer… and maybe someday i might just show up out of the blue and take you up on it!
日本語がわかりますか？私も数学を勉強したいです！
I’d like to study more of math through code
I do know a little Japanese. 
I passed the JLPT N3 in 2019. ( Currently still preparing for the N2 exam. )
Also I am in this awesome JP study group, where ppl post some creative stuff from time to time; u know music and comics and such…
Anyway, that is how I started doing cover songs on youtube! lol For example:
https://www.youtube.com/watch?v=-ZHMGiSXRQA
( I am also trying to put lyrics, chords, vocab and a bit of grammar in the description. )
Aaaaanyway, since quitting clj I had a lot more time for doing math-puzzles,… idk… somehow one thing let to another… and that’s how I ended up creating such puzzles myself. 
Hopefully u find them to be somewhat 面白い;… anywho… here goes nothing…
This math-puzzle is about that time my high-school-class took a trip to the beach.
When we arrived nobody yelled “海だ！” and also nobody felt like playing that awesome water-melon-piñata game. Why? Because the entire class was divided into two opposing camps, A and B, and the members from those groups did not get along, at all, hence, as u can imagine, the overall mood wasn’t terribly cheerful.
Anywho, both groups decided they wanted to build a sandcastle with a moat, but there was only one single bucket available that could be used for fetching water from the sea.
Because I feared that this predicament might lead to a huge fight, I felt like I had to come up with a solution, and PRONTO!
So my plan was to handle the needed sea-water-deliveries to both caste-construction-sites myself, by running like forrest, forrest gump. I would move:
… → A → water → B → water → A → …
But if I was to stand a chance against seepage I had to make sure I took the shortest path possible each time I cleared the distance between A and B.
Consider the following illustration to get a better idea the situation:
Can u spot the shortest path possible? How long is it?
Good luck everyone!
So… many many moons and suns ago, when I was still a constantly daydreaming high school pupil, my class thought that it would be dope to design a poster for the upcoming 文化祭 that showed our 5 favorite kinds of sleeves:
Puff sleeve (because puff means brothel in German and when u r still in 高校 that is p funny to u.)
Batwing sleeve (because it sounds like batman and when u r still in 高校 that is enough to make it cool; ez.)
Juliet sleeve (because that reminds one of Shakespeare and everybody digs that dude!)
Mutton sleeve (because we thought it would be funny to have our school mascot (a sheep) wear those.)
Wizard’s sleeve (because that is obviously an awesome-sounding name for a sleeve to have!)
Anyway, the discussion about the order in which we wanted to print our TOP 5 sleeves onto our poster was very controversial / heated and seamed to drag on forever.
Consider the following illustration showing 3 of the possible orderings that were discussed:
Anyway, the girl who sat next to me, she gave me a slight nudge, because I was all lost in contemplation about my recent Sisyphus-experience at the beach. So I turn to her all startled: “What is it?” and she goes: “There is just no end to this! At this point we have probably discussed already every single ordering of sleeves possible! I mean, how many could there be in total?!”
I replied: “Why, that’s an interesting question!” Here is what I think is the answer: ( I typed something into my faithful pocket calc and showed it to her. )
Her reaction was: “WOW! But there are only 5 sleeves! Hmm, I wonder how many possible orderings there would be, if we had not just 5 sleeves, but as many as there are orderings for those 5?”
“Nop” I smiled “that’s a huge number!.. and this time I can’t do it in my head, but my calculator sure can help us out again; look” and once more I presented to her my dear 相棒’s display.
“WOOOOW, holy moly!!! That’s a lot of zeros at the end there!” she exclaimed.
“Indeed” I agreed.
But how many zeros are there exactly?
Can u help us figure out the answer, so we do not have to actually count them, one by one, off the screen?
Best of luck everyone!
Okay, back in high school I guess I spend most of my afternoons practicing competitive karuta.
Anyway, in order to keep this as simple as possible, suffice it to say that there are 100 different poems / cards in 競技かるた, but only half of those are selected, AT RANDOM, to be in the game. ( The other 50 cards are called 空札. )
Now, there used to be 3 poems that I fancied WAAAAY more than the rest of the lot.
Here is one of them for u… just to give u an idea.
In fact, if at least one of my favorites was in the game, I used to feel perfectly at ease before the start of the match.
What is the probability of that happening?
Good luck everyone!
The great German mathematician Gauss found, at age 17, a value for cos(360°/17). That way he was able to show that one can construct a regular convex 17-gon using ruler and compass.
I am telling you this, because, back in the day, the most popular girl at my high school, she was also the math-club’s president, and she proofed, fully independently, the same thing for the 65537-gon, at age 65537/16^3.
Anyway, everybody told me that trying to 告白 to her was entirely pointless, since the only thing she was interested in was mathematics, but I stubbornly refused to accept this 無駄美人 myth, which is why I seriously considered quitting karuta and to join her math-club instead.
Now it used to be common knowledge, that she presented everybody who wanted to join, with a pretty tough admission question and tbh, at the time, I did not know the first thing about math whatsoever, so one could perhaps argue that my plan was, right from the outset, suffering from something of a major shortcoming, but I was still young, thought ‘頑張って’ to myself, threw the dice up high and knocked at the math-club-room’s door; sweaty handed.
Now everything about the math-club-president was just ridiculously charming, so I was over the moon just talking to her, but all too soon time came for my admission-test and with that ドキドキ turned ビクビク.
Anyway, she handed me the following piece of paper:
As soon as I layed eyes on that multiplication table, I somehow felt immediately like I was in serious trouble.
She smiled.
I trembled.
She: “You ready?”
Me: “えっと”
She: “No worries. This won’t take long.”
Me: “ええっと”
She grinned.
I panicked.
She: “So, I am gonna ask you a question now. After that you have 60 seconds to come up with an answer that I find to be satisfying enough.”
Me: “えええっと”
She: “What do all of these numbers add up to?”
Me: “ええええ！？”
She: “59”
Me: “Does that mean I am supposed to calculate that it in my head?!”
She: “57”
I understood immediately, that I had to make the most of every single second I was given, so I focused as hard as I possibly could on those numbers; read them from left to right, from right to left, from top to bottom, from bottom to top…
Suddenly my brian was somehow able to switch into ‘overdrive-mode’ and I realized that rather miraculously I had managed to enter ‘the zone’, became fully aware of how things had mathemagically begun clicking inside my mind.
What a rush! Never had I experienced anything like this before in my entire life. It felt incredibly 気持ちいい！
She: “4”
She: “3”
Countless digits were still dancing elegantly through my head, like 桜 in a gentle spring breeze.
She: “2”
Me: “付き合ってください！”
She: “
です。”
おしまい。
Would you have been able to please the president?
Best of luck everyone.
Sometimes high school, for me at least, could also kinda suck!
For example, things had gotten p miserable after the entire 告白-fiasco at the math-club-try-out.
Honestly, if it hadn’t been for かるた, things would have been, like the worst, I suppose, especially since I, never mind her shooting me down like a texan-sharpshooter, still had a MAJOR crush on the 部長.
Anyway, so, not even to get over her, but just in order to get by, I would focus all my time and energy on practice:
arm-swings for taking cards as fast and with as much precision as possible
breathing technique for improved multi-syllable-card-timing
card placement strategies
…
Although it may sound weird, those were the sort of things I cared about above all else back then, and luckily that turned out to be remarkably wholesome, since it provided me with some escape / relief / distraction from them “The Sorrows of Young Werther” feels.
Basically one could say, that my recovery proceeded a pace, but then, alas, fully unbeknownst to anyone, that fateful evening had arrived, which would change my entire life in the most dramatic way imaginable.
Here is what transpired:
Since on the next day my school was hosting a somewhat largish かるた-event, our usual hangout simply would not do, so it had been decided to move the needed 畳 over to the gym.
It was quite a bit of work and so after we had managed to set everything up properly, everyone on the かるた-team, including yours truly, was totally 疲れた, so naturally everybody went home to get some rest.
Everybody except me that is, because, in my heart of hearts, I knew that かるた was the only thing that could keep my thoughts from gravitating around her like planets around their sun, from surrendering to her surreal forces of attraction, from becoming pulled in ever closer and closer, from what seamed like the only possible and inescapable outcome, namely to crash and burn.
So there I was, all by myself, kneeling on 畳, solemnly arranging those cards that meant the world to me, taking refuge and comfort in the sheer otherworldly beauty of this poetry that, although composed many hundreds of years ago, could still resonate so powerfully within my juvenile heart.
As luck would have it, all of my three favorite poems, my most trusted allies, they were all sitting there right in front of me, helping me get through these tough times of trials and tribulations.
I took a deep breath.
“Maybe I’ll finally be able to catch a break; for once” I hoped.
I felt at peace and began to memorize the various card-positions.
“よし, lets do this” I whispered to myself and pressed the start button.
“難波津に 咲くやこの花 冬ごもり いまを春べと 咲くやこの花”
Curious things really do happen you know. I was totally beat, but hearing those words was all it took for me to fully recover in each and every way.
お手つき？
ふざけないでよ！
I was playing the game of my life! Playing my heart out! All alone.
And then my ears picked it up:
“しの”
BAAAM!!!
That 決まり字 somehow triggered my entire body to instantly react in the most violent way possible; I swung so hard at that card,… like u would not believe,… send it flying all across the floor.
To recuperate the card, I hurriedly scrambled after it, and that is how I almost ended up literally running into… HER!
“部長？！” I stuttered in dismay.
She: “こんばんは. Interesting mats u got there.”
Me: “HUH?!”
She: “You see, I just came by, because I was told to lock up before leaving. Then I saw those curious 2x1 mats and that got me thinking about how many ways one could tile an MxN region using them.”
Me: “…And, did you figure it out?”
She: “Sure did.”
She beamed.
I was still feeling as flabbergasted as confused.
Me: “So what’s the answer?”
She: “I could tell you, but I am afraid you wouldn’t understand.”
She: “No offence.”
Me: “None taken.”
She: “Actually, you know what, ever since u came to the club-room, I have kinda been meaning to talk to you, but you seamed rather stressed out about it, and so I figured it would perhaps be best to let things go for the sake of minimizing awkwardness.”
Me: “Club-room?.. Oh… right… but that’s like ancient history to me,… already forgot all about it tbh, so… no worries.”
She: “Look, since things didn’t work out too well last time, I’ll let u have one more shot at it, if u r still interested, that is.”
Me: “Hit me!”
She: “How many ways can one tile a 2x9 region using such 2x1 mats？ Again, u have one minute; 頑張って.”
Me: “マジか？”
She: “59”
I closed my eyes, tried to focus on the problem at hand, but with her standing there right next to me, wearing that perfume and all, I realized that this was totally 無理.
Me: “狡い。”
She: “43”
Me: “狡いよ！”
She: “42！”
Me: “結婚して下さい！”
She: “:-)”
She: “馬鹿！本当に！”
She: “ ですよ！”
She: “Also, why wouldn’t you simply ask me out for coffee like a normal person?! 馬鹿！”
Me: “Coffee sounds great! …じゃあデートです!”
She smiled.
Me too.
She: “Also, you are so not on the math-team!”
Me: “はい”
She: “馬鹿！”
Me: “はい”
おしまい。
Would you have been able to make the team this time?
Best of luck everyone!
p.s. the tatami-mats are of the normal plain type; they all look the same and they do not have any sort of weird asymmetric patterns on them.
p.s. wood pic from wikipedia:
CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=46641
So much like!!! I also play Karuta (the northern Hokkaido style).
I will write a longer reply once I’ve had some sleep
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