This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A175531 #21 Apr 20 2024 05:55:47 %S A175531 443372888629441,39671149333495681,842526563598720001, %T A175531 2380296518909971201,3188618003602886401,4208895375600667752001 %N A175531 Carmichael numbers of order 2. %C A175531 Odd composite integer k is in this sequence if k == 1 or p (mod p^2 - 1) for every prime p|k. %H A175531 Claude Goutier, <a href="http://www-labs.iro.umontreal.ca/~goutier/OEIS/A055553/">Compressed text file carm10e22.gz containing all the Carmichael numbers up to 10^22</a>. %H A175531 Everett W. Howe, <a href="https://doi.org/10.1090/S0025-5718-00-01225-4">Higher-order Carmichael numbers</a>, Math. Comp. 69 (2000), 1711-1719. doi:10.1090/S0025-5718-00-01225-4 %Y A175531 Subsequence of A002997, A175530, and A299799. %K A175531 nonn,hard,more %O A175531 1,1 %A A175531 _Max Alekseyev_, Jun 08 2010 %E A175531 a(6) calculated using data from _Claude Goutier_ and added by _Amiram Eldar_, Apr 20 2024