%I
%S 1,2,8,32,256,4096,65536,2097152,134217728,8589934592,1099511627776,
%T 281474976710656,72057594037927936,36893488147419103232,
%U 37778931862957161709568,38685626227668133590597632
%N Hankel transform of expansion of (1/(1x^2))c(x/(1x^2)), where c(x) is the g.f. of A000108.
%C Hankel transform of A105864.
%C The sequence 1,1,2,8,... with general term 2^floor(n^2/3) is the Hankel transform of A109033. [From _Paul Barry_, Dec 14 2008]
%C a(n)=4*e(n1)*e(n3)/e(n4). Somos4 sequence associated to e.g. y^2=18x+16x^28x^3. [From _Paul Barry_, Nov 27 2009]
%F a(n)=2^floor((n+1)^2/3); a(n)=Product{k=1..n, (5/32*cos(2*pi*k/3)/3)^(nk+1)}; a(n)=Product{k=1..n, A130196(k)^(nk+1)};
%K easy,nonn
%O 0,2
%A _Paul Barry_, Nov 08 2007
