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 A291745 #20 Jul 02 2024 08:22:06 %S A291745 1,4,10,16,22,25,28,34,40,46,49,52,55,58,64,70,76,82,85,88,91,94,100, %T A291745 106,112,115,118,121,124,130,133,136,142,145,148,154,160,166,169,172, %U A291745 175,178,184,187,190,196,202,205,208,214,217,220,226,232,235,238,244,247 %N A291745 Nonprimes of the form 3*k + 1. %C A291745 Subsequence of A018252. A091300 is a subsequence. %C A291745 A multiplicative semigroup: if m and n are in the sequence, then so is m*n. - _Antti Karttunen_, Jul 02 2024 %H A291745 Vincenzo Librandi, <a href="/A291745/b291745.txt">Table of n, a(n) for n = 1..1600</a> %t A291745 DeleteCases[3 Range[0, 300] + 1, _?PrimeQ] %o A291745 (Magma) [n: n in [1..400 by 3] | not IsPrime(n)]; %Y A291745 Cf. A002476, A016777, A091113, A091300, A291746, A291747, A373977 (characteristic function). %K A291745 nonn,easy %O A291745 1,2 %A A291745 _Vincenzo Librandi_, Aug 31 2017