a(n) = (18*n)!*(2*n)!/((9*n)!*(6*n)!*(5*n)!).A295445a(n) = (18*n)!*(2*n)!/((9*n)!*(6*n)!*(5*n)!).Terms a(0) =1a(1) =408408a(2) =802241960520External referencesoeis: A295445