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A127134
Central terms of triangle A127126; a(n) = A127126(2n,n).
7
1, 2, 18, 284, 6680, 211398, 8439235, 407247048, 23056215138, 1498169721930, 109876657252604, 8976437481923520, 808257688877060396, 79516093326076500590, 8485004019719253675540, 976009472808194554659440
OFFSET
0,2
COMMENTS
a(n) is divisible by (n+1): a(n)/(n+1) = A127135(n).
LINKS
MATHEMATICA
T[n_, k_]:= T[n, k]= If[k==n, 1, Coefficient[(1 +x*Sum[x^(r-k-1)*Sum[T[r, c], {c, k+1, r}], {r, k+1, n}] +x^(n+1))^(k+1), x, n-k]]; Table[T[2*n, n], {n, 0, 20}] (* G. C. Greubel, Jan 28 2020 *)
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Jan 05 2007
STATUS
approved