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 A366609 #13 Jan 08 2024 16:47:36 %S A366609 2,5,17,5,257,5,17,5,65537,5,17,5,97,5,17,5,641,5,17,5,257,5,17,5,193, %T A366609 5,17,5,257,5,17,5,274177,5,17,5,97,5,17,5,65537,5,17,5,257,5,17,5, %U A366609 641,5,17,5,257,5,17,5,449,5,17,5,97,5,17,5,59649589127497217 %N A366609 Smallest prime dividing 4^n + 1. %H A366609 Max Alekseyev, <a href="/A366609/b366609.txt">Table of n, a(n) for n = 0..1983</a> %Y A366609 Bisection of A002586. %Y A366609 Cf. A002586, A038371, A052539, A074476, A274903, A366605, A366606, A366607, A366608, A366670, A366671, A366719. %K A366609 nonn %O A366609 0,1 %A A366609 _Sean A. Irvine_, Oct 14 2023