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