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 A129110 #4 Mar 30 2012 18:51:51 %S A129110 1,2,1,-1,1,6,1,-13,1,43,1,-131,1,430,1,-1429,1,4863,1,-16795,1,58787, %T A129110 1,-208011,1,742901,1,-2674439,1,9694846,1,-35357669,1,129644791,1, %U A129110 -477638699,1,1767263191,1,-6564120419,1,24466267021,1,-91482563639,1,343059613651 %N A129110 A transformation of the Catalan sequence. %F A129110 a(2n)=1. a(2n+1)= 1+(-1)^n*C(n+1), where C=A000108. %F A129110 a(n+1)-a(n) = A129996(n) (similar to A099363 and A106181). %K A129110 sign %O A129110 0,2 %A A129110 _Paul Curtz_, May 24 2007 %E A129110 Edited and extended by _R. J. Mathar_, Jul 04 2008