a(n) = 4*n^3.

Terms

a(0) =0a(1) =4a(2) =32a(3) =108a(4) =256a(5) =500a(6) =864a(7) =1372a(8) =2048a(9) =2916a(10) =4000a(11) =5324a(12) =6912a(13) =8788a(14) =10976a(15) =13500a(16) =16384a(17) =19652a(18) =23328a(19) =27436a(20) =32000a(21) =37044a(22) =42592a(23) =48668a(24) =55296a(25) =62500a(26) =70304a(27) =78732a(28) =87808a(29) =97556