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 A037204 #3 Mar 31 2012 13:50:35 %S A037204 6,22,30,41,44,50,52,80,86,89,96,98,112,115,121,142,156,173,177,257, %T A037204 270,295,303,326,337,343,349,355,361,370,380,383,387,400,402,409,419, %U A037204 421,424,449,452,454,463,473,490,500 %N A037204 Numbers that occur in runs of length 1 in A037203. %e A037204 A037201 contains "...,5,5,"6",7,7,7,7,7...", with a single 6; so a(1)=6. %K A037204 easy,nonn %O A037204 0,1 %A A037204 _Naohiro Nomoto_