a(n) = n*(4*n+1).

Terms

a(0) =0a(1) =5a(2) =18a(3) =39a(4) =68a(5) =105a(6) =150a(7) =203a(8) =264a(9) =333a(10) =410a(11) =495a(12) =588a(13) =689a(14) =798a(15) =915a(16) =1040a(17) =1173a(18) =1314a(19) =1463a(20) =1620a(21) =1785a(22) =1958a(23) =2139a(24) =2328a(25) =2525a(26) =2730a(27) =2943a(28) =3164a(29) =3393