a(n) = 5*4*3*2*1 + 10*9*8*7*6 + 15*14*13*12*11 + ... + (up to the n-th term).

Terms

a(0) =5a(1) =20a(2) =60a(3) =120a(4) =120a(5) =130a(6) =210a(7) =840a(8) =5160a(9) =30360a(10) =30375a(11) =30570a(12) =33090a(13) =63120a(14) =390720a(15) =390740a(16) =391100a(17) =397560a(18) =507000a(19) =2251200a(20) =2251225a(21) =2251800a(22) =2265000a(23) =2554800a(24) =8626800a(25) =8626830a(26) =8627670a(27) =8651160a(28) =9284520a(29) =25727520