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 A291747 #9 Sep 08 2022 08:46:19 %S A291747 1,8,15,22,36,50,57,64,78,85,92,99,106,120,134,141,148,155,162,169, %T A291747 176,183,190,204,218,225,232,246,253,260,267,274,288,295,302,309,316, %U A291747 323,330,344,351,358,365,372,386,393,400,407,414,428,435,442,456,470,477,484,498 %N A291747 Nonprimes of the form 7*k + 1. %C A291747 Subsequence of A018252. %t A291747 DeleteCases[7 Range[0, 200] + 1, _?PrimeQ] %o A291747 (Magma) [n: n in [1..500 by 7] | not IsPrime(n)]; %Y A291747 Cf. A016993, A091113, A091300, A140444, A291745, A291746. %K A291747 nonn,easy %O A291747 1,2 %A A291747 _Vincenzo Librandi_, Aug 31 2017