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 A020947 #3 Mar 30 2012 18:55:50 %S A020947 2,6,15,14,28,61,30,58,121,60,62,116,241,120,245,122,124,469,234,806, %T A020947 509,254,242,248,244,252,250,466,510,468,494,482,486,977,488,484,504, %U A020947 492,930,490,506,936,500,932,940,966 %N A020947 Least k such that A(k) = n, where A( ) is sequence A020943. %Y A020947 Cf. A020943-A020945, A002487, A020948-A020950. %K A020947 nonn %O A020947 1,1 %A A020947 _Clark Kimberling_