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 A306222 #8 Jan 30 2019 05:36:35 %S A306222 60,84,93,96,123,132,135,147,150,156,162,185,194,197,209,212,218,224, %T A306222 232,235,241,247,249,283,292,295,307,310,316,322,330,333,339,345,347, %U A306222 366,369,375,381,383,396,439,448,451,463,466,472,478,486,489,495,501,503 %N A306222 Positions of 4's in A306211. %H A306222 Rémy Sigrist, <a href="/A306222/b306222.txt">Table of n, a(n) for n = 1..25000</a> %Y A306222 Cf. A306211, A306223, A323476. %K A306222 nonn %O A306222 1,1 %A A306222 _Rémy Sigrist_, Jan 30 2019