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 A031318 #4 Mar 30 2012 18:56:23 %S A031318 3,11,21,31,41,46,48,50,51,52,54,61,71,81,91,104,119,134,149,164,172, %T A031318 175,178,179,181,184,194,209,224,239,254,269,284,299,314,322,325,328, %U A031318 329,331,334,344,359,374,389,404,419,434,449 %N A031318 Position of n-th 5 in A031312. %K A031318 nonn %O A031318 1,1 %A A031318 _Clark Kimberling_