a(n) = n^4 - 2n.

Terms

a(0) =0a(1) =-1a(2) =12a(3) =75a(4) =248a(5) =615a(6) =1284a(7) =2387a(8) =4080a(9) =6543a(10) =9980a(11) =14619a(12) =20712a(13) =28535a(14) =38388a(15) =50595a(16) =65504a(17) =83487a(18) =104940a(19) =130283a(20) =159960a(21) =194439a(22) =234212a(23) =279795a(24) =331728a(25) =390575a(26) =456924a(27) =531387a(28) =614600a(29) =707223