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 A031316 #4 Mar 30 2012 18:56:23 %S A031316 2,9,19,26,28,29,30,32,34,39,49,59,69,79,89,101,116,131,142,145,146, %T A031316 148,151,154,161,176,191,206,221,236,251,266,281,292,295,296,298,301, %U A031316 304,311,326,341,356,371,386,396,399,401,402,405 %N A031316 Position of n-th 3 in A031312. %K A031316 nonn %O A031316 1,1 %A A031316 _Clark Kimberling_