a(n) = (n + 1)*(6*n^2 + 15*n + 4)/2.

Terms

a(0) =2a(1) =25a(2) =87a(3) =206a(4) =400a(5) =687a(6) =1085a(7) =1612a(8) =2286a(9) =3125a(10) =4147a(11) =5370a(12) =6812a(13) =8491a(14) =10425a(15) =12632a(16) =15130a(17) =17937a(18) =21071a(19) =24550a(20) =28392a(21) =32615a(22) =37237a(23) =42276a(24) =47750a(25) =53677a(26) =60075a(27) =66962a(28) =74356a(29) =82275