This is not a SFW instance. NSFW communities will be tagged, and efforts will be made to keep SFW communities clean, but proceed at your own comfort level.
Hmmm, could be numbers k such that phi(k) divides k+1, where phi is Euler’s totient function or perhaps numbers k such that every base-4 digit of k is a base-6 digit of k? Quite the puzzler.
Hmmm, could be numbers k such that phi(k) divides k+1, where phi is Euler’s totient function or perhaps numbers k such that every base-4 digit of k is a base-6 digit of k? Quite the puzzler.
https://oeis.org/search?q=1%2C2%2C3%2C15&language=english&go=Search