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 A031002 #4 Mar 30 2012 18:56:19 %S A031002 3,14,28,35,37,39,41,42,43,45,47,56,70,84,102,123,144,155,158,161,164, %T A031002 165,167,170,173,186,207,228,249,270,291,302,305,308,311,312,314,317, %U A031002 320,333,354,375,385,388,391,394,396,397,400 %N A031002 Position of n-th 3 in A030998. %K A031002 nonn %O A031002 1,1 %A A031002 _Clark Kimberling_