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 A255491 #9 Sep 08 2022 08:46:11 %S A255491 1,4,5,8,10,12,14,15,16,19,21,22,23,27,29,30,32,35,36,38,40,42,43,44, %T A255491 46,48,49,50,52,53,56,57,58,59,60,61,63,64,66,67,71,75,77,78,79,80,81, %U A255491 82,83,85,87,88,92,93,95,99,103,104,105,106 %N A255491 Numbers k such that 90*k+1 is composite. %D A255491 J. W. Helkenberg, Email message, Mar 02 2015. %H A255491 Vincenzo Librandi, <a href="/A255491/b255491.txt">Table of n, a(n) for n = 1..7000</a> %t A255491 Select[Range[200], !PrimeQ[90 # + 1] &] (* _Vincenzo Librandi_, Jun 09 2017 *) %o A255491 (Magma) [n: n in [1..120]| not IsPrime(90*n+1)]; // _Vincenzo Librandi_, Jun 09 2017 %Y A255491 Complement of A181732. %K A255491 nonn %O A255491 1,2 %A A255491 _N. J. A. Sloane_, Mar 03 2015