a(n) = (n - 1)*(4*n^2 - 8*n + 5).

Terms

a(0) =0a(1) =5a(2) =34a(3) =111a(4) =260a(5) =505a(6) =870a(7) =1379a(8) =2056a(9) =2925a(10) =4010a(11) =5335a(12) =6924a(13) =8801a(14) =10990a(15) =13515a(16) =16400a(17) =19669a(18) =23346a(19) =27455a(20) =32020a(21) =37065a(22) =42614a(23) =48691a(24) =55320a(25) =62525a(26) =70330a(27) =78759a(28) =87836a(29) =97585