I have made a symbol to represent 𝛕 (=2π), it is a scheme of how a circle opens and straightens. In the second figure more steps are added, the curve defined by the endpoints is a cochleoid. Finally the third figure shows a tau spider.
UPDATE: My program found a new personal best most delayed palindromic number!
The 25-digit number 1102320000659911613429286 takes 235 iterations before it becomes a 123-digit palindrome.
This beats a former world record set in 2003 by Jason Doucette involving 233 iterations (source: https://jasondoucette.com/worldrecords.html#Most), and is 58 iterations off from the current world record of 293.
#Math #LychrelNumber #MostDelayedPalindromicNumber #Mathematics #RecMath #RecreationalMathematics
((10^n)-1)*(2/3)-53, a formula resulting in rows of n number of sixes with the last two sixes replaced with the number 13, result in primes for n = 2, 3, 7, 12, 30, 97, 192, 265, 327, 417, 475, 574, 595, 699, 9563, and 9601. 
Update: It's ran for 10 days and hasn't found any other new primes below n = 37000. Stopping the program now!
#Math #Mathematics #PrimeNumbers #RecreationalMath #RecMath #RecreationalMathematics #Primes
Update: New record! After appending random digit after random digit for two days, it eventually found this 31689-digit prime. It's larger than the 148091th number in the Fibonacci sequence, which is also prime.
The tiny white digits on the black background look like TV static when zoomed out!
#Math #Mathematics #PrimeNumbers #Primes #RecreationalMathematics #RecMath
Update: overnight it found a 17828-digit prime number, a new personal best!
I can see why most primes found are found with easy-to-write formulae like (2^p)-1 or (k^2^n)+1. Ttrying to go backwards – coming up with a compact formula to represent a really huge prime made up of random digits like this one, is really tricky.
#Math #Mathematics #PrimeNumbers #Primes #RecreationalMathematics #RecMath
Just for fun, I wrote a Python program to start with a random decimal digit, and keep adding the decimal digit until it reaches a prime number.
I'm excited to share it's found a 10997-digit long prime number, which is my new personal best largest prime! It's larger than the 37th factorial prime (3507!-1) which is 10912 digits.
I'll leave the program running overnight to see if it can find longer ones!
#Math #Mathematics #PrimeNumbers #Primes #RecreationalMathematics #RecMath
TIL there is #RecreationalMathematics, and D. R. Kaprekar was a "recreational mathematician".
Dani Laura (they/she/he)
greatquux
MOULE 
Adam R. Wood
katzenberger 🇺🇦