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%I #3 Mar 30 2012 18:37:03
%S 1,1,4,17,98,622,4512,35373,300974,2722070,26118056,263266346,
%T 2780054884,30586452652,349724463584,4141218303165,50678688359190,
%U 639387728054310,8302396672724280,110754894628585950
%N Column 0 of triangle A128320.
%F a(n) = Sum_{k=0..[n/2]} A000108(n-k)*A000108(k)*(k+1)!*C(n,2k) where A000108 is the Catalan numbers. a(n) = Sum_{k=0..[(n+1)/2]} C(2(n-k),n-k)/(n-k+1)*C(2k,k)/(k+1)*(k+1)!*C(n,2k).
%o (PARI) {a(n)=sum(k=0,n\2,binomial(2*n-2*k,n-k)/(n-k+1)*binomial(2*k,k)/(k+1) *(k+1)!*binomial(n,2*k))}
%Y Cf. A128320 (triangle), A128322 (column 1), A128323 (column 2), A128324 (row sums); variant: A115081.
%K nonn
%O 0,3
%A _Paul D. Hanna_, Feb 25 2007
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