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 A316840 #7 Jul 23 2018 09:04:55 %S A316840 7,22,36,51,63,78,92,107,115,130,144,159,171,186,200,215,230,244,259, %T A316840 271,286,300,315,323,338,352,367,379,394,408,423,437,452,464,479,493, %U A316840 508,516,531,545,560,572,587,601,616,631,645,660,672,687,701,716,724,739,753,768,780,795,809,824 %N A316840 Indices of 3's in A254990. %H A316840 Seiichi Manyama, <a href="/A316840/b316840.txt">Table of n, a(n) for n = 1..10000</a> %Y A316840 Cf. A254990, A316837, A316838, A316839. %K A316840 nonn %O A316840 1,1 %A A316840 _N. J. A. Sloane_, Jul 22 2018