a(n) = (2*n - 11)*n^2.

Terms

a(0) =0a(1) =-9a(2) =-28a(3) =-45a(4) =-48a(5) =-25a(6) =36a(7) =147a(8) =320a(9) =567a(10) =900a(11) =1331a(12) =1872a(13) =2535a(14) =3332a(15) =4275a(16) =5376a(17) =6647a(18) =8100a(19) =9747a(20) =11600a(21) =13671a(22) =15972a(23) =18515a(24) =21312a(25) =24375a(26) =27716a(27) =31347a(28) =35280a(29) =39527