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 A228575 #34 Aug 25 2019 17:55:36 %S A228575 645,656601,6212361,18958567881,287468425245,626160901281, %T A228575 1395494019921,1925525109201,1960708164801,1962378065901, %U A228575 1977370759365,2788325761551,3032013857181,6877227801081,22298617759881,30242009317521,39454593651201,42401101442001 %N A228575 Pseudoprimes n to base 2 such that n-4, n-2 and n+2 are primes. %C A228575 All numbers in this sequence end in either 5 or 1. %H A228575 Shyam Sunder Gupta, <a href="/A228575/b228575.txt">Table of n, a(n) for n = 1..831</a> %e A228575 645 is a pseudoprime (base 2) and 641, 643 and 647 are primes. %Y A228575 Cf. A001567, A057942, A230488, A230489. %K A228575 nonn %O A228575 1,1 %A A228575 _Shyam Sunder Gupta_, Oct 27 2013