a(n) = (n+1)^4*(4+n)!/24.A154307a(n) = (n+1)^4*(4+n)!/24.Terms a(0) =1a(1) =80a(2) =2430a(3) =53760a(4) =1050000a(5) =19595520a(6) =363031200a(7) =6812467200a(8) =130947062400External referencesoeis: A154307