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A359761

a(n) = binomial(4*n, 2*n)*(2*n)!/(2^n*n!).

1, 6, 210, 13860, 1351350, 174594420, 28109701620, 5421156741000, 1218404977539750, 312723944235202500, 90252130306279441500, 28929910132721937339000, 10197793321784482911997500, 3920659309406065045704885000, 1632674555274097086889962825000, 732091270584905133761459330730000

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..15.

FORMULA

a(n) = (2^(3*n)*Gamma(2*n + 1/2))/(sqrt(Pi)*Gamma(n + 1)).

a(n) = A359760(4*n, 2*n), the central terms of the triangle without the zeros.

a(n) = A001448(n)*A001147(n). - R. J. Mathar, Jan 25 2023

D-finite with recurrence n*a(n) -2*(4*n-1)*(4*n-3)*a(n-1)=0. - R. J. Mathar, Jan 25 2023

MAPLE

a := binomial(4*n, 2*n)*(2*n)!/(2^n*n!):