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 A030391 #4 Mar 30 2012 18:56:18 %S A030391 1,2,3,11,5,1,9,19,8,15,2,3,10,18,25,75,31,11,63,30,5,6,47,33,7,14,1, %T A030391 36,9,22,72,123,34,82,19,62,46,13,8,81,58,15,16,2,70,17,24,27,3,85, %U A030391 133,10,49,68,21,18,61,109,23,26,73,121,25,427,176 %N A030391 a(n)=least k such that base 4 representation of n begins at s(k), where s=A030386. %K A030391 nonn %O A030391 1,2 %A A030391 _Clark Kimberling_