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 A181030 #10 Sep 19 2015 17:35:28 %S A181030 1,2,7,63,1234,55447,5598861,1280128950,660647962955,770548397261707, %T A181030 2030049051145980050,12083401651433651945979, %U A181030 162481813349792588536582997,4935961285224791538367780371090,338752110195939290445247645371206783 %N A181030 Duplicate of A006506. %H A181030 R. H. Hardin, <a href="/A181030/b181030.txt">Table of n, a(n) for n = 1..21</a> %F A181030 Conjecture: a(n) = A006506(n-1), n>1. - _R. J. Mathar_, Oct 02 2010 %Y A181030 Diagonal of A181031. %K A181030 dead %O A181030 1,2