a(n) = (20*n)!*(3*n)!/((10*n)!*(9*n)!*(4*n)!).A295475a(n) = (20*n)!*(3*n)!/((10*n)!*(9*n)!*(4*n)!).Terms a(0) =1a(1) =461890a(2) =935387159850External referencesoeis: A295475