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a(n) = Sum_{k=1..n-1} binomial(n, k)*G_n*G_{n-k} where G_n is the n-th Genocchi number (of the first kind).
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%I #14 Aug 10 2017 06:45:07

%S 2,-6,6,10,-30,-42,238,306,-2790,-3410,45606,53898,-993902,-1146810,

%T 27887070,31605346,-979901046,-1095183522,42166810390,46605422010,

%U -2181617832702,-2389390959626,133636947954126,145257552124050,-9566483624198150,-10331802314134002

%N a(n) = Sum_{k=1..n-1} binomial(n, k)*G_n*G_{n-k} where G_n is the n-th Genocchi number (of the first kind).

%H Seiichi Manyama, <a href="/A290701/b290701.txt">Table of n, a(n) for n = 2..549</a>

%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Genocchi_number">Genocchi number</a>

%F a(n) = 2*n*A036968(n-1) + 2*(n-1)*A036968(n).

%Y Cf. A036968.

%K sign

%O 2,1

%A _Seiichi Manyama_, Aug 09 2017