a(n) = n*(n^2 + 1) if n is even, otherwise (n - 1/2)*(n^2 + 1).

Terms

a(0) =0a(1) =1a(2) =10a(3) =25a(4) =68a(5) =117a(6) =222a(7) =325a(8) =520a(9) =697a(10) =1010a(11) =1281a(12) =1740a(13) =2125a(14) =2758a(15) =3277a(16) =4112a(17) =4785a(18) =5850a(19) =6697a(20) =8020a(21) =9061a(22) =10670a(23) =11925a(24) =13848a(25) =15337a(26) =17602a(27) =19345a(28) =21980a(29) =23997