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 A106189 #4 Mar 30 2012 18:59:07
%S A106189 1,2,8,24,86,300,1096,4032,15062,56684,214880,818800,3133916,12038200,
%T A106189 46384432,179193920,693849254,2691994060,10462833808,40729251920,
%U A106189 158772196436,619716378280,2421643356592,9472863484160,37090890396284
%N A106189 Expansion of 1/((1-2x^2)sqrt(1-4x)).
%C A106189 Diagonal sums of A112336. - _Paul Barry_, Sep 04 2005
%F A106189 a(n)=sum{k=0..floor(n/2), binomial(2(n-2k), n-2k)*2^k}.
%K A106189 easy,nonn
%O A106189 0,2
%A A106189 _Paul Barry_, Apr 24 2005