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 A228846 #28 Feb 16 2025 08:33:20 %S A228846 1,2,4,8,16,7,8,9,11,16,14,14 %N A228846 Largest m such that (2k+1)*2^m + 1 is a prime factor of the Fermat number 2^(2^n) + 1. %C A228846 a(n) >= n + 2 for n >= 2. %C A228846 a(n) = A228845(n) if 2^(2^n) + 1 is prime or semiprime. %C A228846 a(n) = max (A007814(p_i-1)), where p_i are the prime factors of 2^(2^n)+1. - _Ralf Stephan_, Sep 09 2013 %C A228846 For n >= 2, a(n) >= n + 3 if A046052(n) is an odd number. - _Arkadiusz Wesolowski_, Aug 10 2021 %H A228846 Wilfrid Keller, <a href="http://www.prothsearch.com/fermat.html">Fermat factoring status</a> %H A228846 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/FermatNumber.html">Fermat Number</a> %e A228846 F(5) = 641*6700417 and max(A007814(640),A007814(6700416))=7, so a(5)=7. %Y A228846 Cf. A000215, A019434, A023394, A046052, A228845. %K A228846 nonn,hard,more %O A228846 0,2 %A A228846 _Arkadiusz Wesolowski_, Sep 05 2013