%I #5 Mar 30 2012 17:22:26
%S 4,40,544,8320,131584,2099200,33562624,536903680,8590065664,
%T 137439477760,2199025352704,35184380477440
%N Sum of coefficients of (x1)^(2i(1))*(x2)^(2i(2))*(x3)^(2i(3))*(x4)^(2i(4)) for {(i1),(i2),(i3),(i4)}=0,1,2,... : sum(i)=2n in the expansion of (x1+x2+x3+x4)^(2n) where n=1,2,3,...
%C For k=3, the sequence divided by 3 is equal to A066443.
%F a(n, 4) = 2^(1-4)*(sum(r=0 to Floor((4-1)/2))Binomial(4, r)*(4-2*r)^2n a(n, k) = 2^(1-k)*(sum(r=0 to Floor((k-1)/2))Binomial(k, r)*(k-2*r)^2n for k=1, 2, 3, 4, ...
%Y Cf. A066443.
%Y Essentially same as A092812. - Kang Seonghoon (lifthrasiir(AT)gmail.com), Oct 09 2008
%K easy,nonn
%O 0,1
%A Jan Hagberg (jan.hagberg(AT)stat.su.se), Oct 16 2002
%E Corrected by _T. D. Noe_, Nov 07 2006