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 A171450 #2 Mar 30 2012 18:59:26 %S A171450 1,1,2,5,15,54,231,1133,6082,34397,200063,1180798,7023103,41946973, %T A171450 251144922,1505966757,9040214223,54314351878,326565963479, %U A171450 1964805696525,11828911080050,71258494789421,429525155047263,2590571415647886 %N A171450 Sequence with Hankel transform given by 2^C(n,2)*2^floor(n/3). %C A171450 Hankel transform is A171451. %F A171450 G.f.: 1/(1-x/(1-x/(1-x/(1-2x/(1-2x/(1-2x/(1-x/(1-x/(1-x/(1-2x/(1-... (continued fraction). %K A171450 easy,nonn %O A171450 0,3 %A A171450 _Paul Barry_, Dec 09 2009