a(n) = 4*n^2 - 9*n + 6.

Terms

a(0) =1a(1) =4a(2) =15a(3) =34a(4) =61a(5) =96a(6) =139a(7) =190a(8) =249a(9) =316a(10) =391a(11) =474a(12) =565a(13) =664a(14) =771a(15) =886a(16) =1009a(17) =1140a(18) =1279a(19) =1426a(20) =1581a(21) =1744a(22) =1915a(23) =2094a(24) =2281a(25) =2476a(26) =2679a(27) =2890a(28) =3109a(29) =3336