a(n) = (2*n - 5)n^2.

Terms

a(0) =0a(1) =-3a(2) =-4a(3) =9a(4) =48a(5) =125a(6) =252a(7) =441a(8) =704a(9) =1053a(10) =1500a(11) =2057a(12) =2736a(13) =3549a(14) =4508a(15) =5625a(16) =6912a(17) =8381a(18) =10044a(19) =11913a(20) =14000a(21) =16317a(22) =18876a(23) =21689a(24) =24768a(25) =28125a(26) =31772a(27) =35721a(28) =39984a(29) =44573