a(n) = n*(5*n - 3)*(25*n^2 - 15*n - 6)/8.

Terms

a(0) =0a(1) =1a(2) =112a(3) =783a(4) =2839a(5) =7480a(6) =16281a(7) =31192a(8) =54538a(9) =89019a(10) =137710a(11) =204061a(12) =291897a(13) =405418a(14) =549199a(15) =728190a(16) =947716a(17) =1213477a(18) =1531548a(19) =1908379a(20) =2350795a(21) =2865996a(22) =3461557a(23) =4145428a(24) =4925934a(25) =5811775a(26) =6812026a(27) =7936137a(28) =9193933a(29) =10595614