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 A166231 #7 May 08 2016 00:40:54
%S A166231 1,4,48,1280,69632,7602176,1660944384,725849473024,634418209226752,
%T A166231 1109011408239984640,3877275019992826380288,
%U A166231 27111105978154633171828736,379138479844261543254652092416,10604214183559196000870296488771584
%N A166231 a(n) = 2^C(n+1,2)*A006012(n).
%C A166231 Hankel transform of A166228, A166229.
%H A166231 G. C. Greubel, <a href="/A166231/b166231.txt">Table of n, a(n) for n = 0..70</a>
%F A166231 a(n) = 2^C(n+1,2)*Sum_{k=0..floor(n/2)} C(n,2k)*2^(n-k).
%F A166231 a(n) = 4^n*A166232(n).
%t A166231 Table[2^(Binomial[n + 1, 2])*Sum[Binomial[n, 2 k]*2^(n - k), {k, 0, Floor[n/2]}], {n, 0, 25}] (* _G. C. Greubel_, May 07 2016 *)
%Y A166231 Cf. A006012, A166228, A166229, A166232.
%K A166231 easy,nonn
%O A166231 0,2
%A A166231 _Paul Barry_, Oct 09 2009