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%I #4 Mar 31 2012 13:20:01
%S 1,3,9,22,54,123,281,618,1362,2934,6330,13452,28620,60243,126921,
%T 265282,554874,1153506,2399390,4966740,10286196,21219038,43790154,
%U 90076452,185353204,380364108,780786516,1599015192,3275589144
%N Second convolution of A001405 (central binomial numbers).
%F a(2*k)= -3*2^(2*k+1)+binomial(2*(k+1), k+1)*(4*k+7)/2, a(2*k+1)= -3*4^(k+1)+binomial(2*(k+2), k+2)*(2*k+5)/2, k >= 0.
%F a(n)= A054336(n+2, 2) (third column of convolution triangle). G.f.: (1/(1-x-x^2*c(x^2)))^3, with c(x) the g.f. for the Catalan numbers A000108.
%Y Cf. A000108, A001405, A054336, A045621.
%K easy,nonn
%O 0,2
%A _Wolfdieter Lang_, Mar 27 2000
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