a(n) = (10n)!*n!/((5n)!*(4n)!*(2n)!).A061163a(n) = (10n)!*n!/((5n)!*(4n)!*(2n)!).Terms a(0) =1a(1) =630a(2) =1385670a(3) =3528923580External referencesoeis: A061163