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%I #4 Mar 31 2012 10:23:14
%S 1,0,-3,15,42,-2895,54417,-251160,-32268603,1859064495,-56137896318,
%T -300966155655,194418466667697,-17000801954550960,829654990634826717,
%U 8111862191577165855,-7601061861134689474758,1057729211267718608758065
%N E.g.f. cos(cos(x)-1) (even part)
%F a(n):=2*(sum(k=0..n, ((-1)^(k)*sum(j=1..2*k, ((sum(i=0..(j-1)/2, (j-2*i)^(2*n)*binomial(j,i)))*binomial(2*k,j)*(-1)^(n-j))/2^j))/(2*k)!)), n>0, a(0)=1.
%o (Maxima)
%o a(n):=if n=0 then 1 else 2*(sum(((-1)^(k)*sum(((sum((j-2*i)^(2*n)*binomial(j,i),i,0,(j-1)/2))*binomial(2*k,j)*(-1)^(n-j))/2^j,j,1,2*k))/(2*k)!,k,0,n));
%K sign
%O 0,3
%A _Vladimir Kruchinin_, Jun 21 2011
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