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 A293291 #8 Aug 27 2021 01:47:15 %S A293291 825265,1210178305,11113519105,230864201601,772350315265, %T A293291 1540032424705,204855497662465,453644962192318465,770522162068767745, %U A293291 3070111619849131585,44428201205269571987560724263876473913345 %N A293291 Carmichael numbers m having a Fermat prime (A019434) factor such that A002322(m) = 2^k * p^2, where k is an integer and p is an odd prime. %C A293291 Tsumura (2017) proved that there are no other such Carmichael numbers if there are only five Fermat primes. %C A293291 The prime p happens to equal 3 or 5 in all cases. %H A293291 Y. Tsumura, <a href="https://arxiv.org/abs/1710.01321">On the finiteness of Carmichael numbers with Fermat factors and L = 2^α P^2</a>, arXiv:1710.01321 [math.NT], 2017. %Y A293291 Cf. A002997, A214428. %K A293291 nonn %O A293291 1,1 %A A293291 _Max Alekseyev_, Oct 05 2017