a(n) = n^2*(2*n+1).

Terms

a(0) =0a(1) =3a(2) =20a(3) =63a(4) =144a(5) =275a(6) =468a(7) =735a(8) =1088a(9) =1539a(10) =2100a(11) =2783a(12) =3600a(13) =4563a(14) =5684a(15) =6975a(16) =8448a(17) =10115a(18) =11988a(19) =14079a(20) =16400a(21) =18963a(22) =21780a(23) =24863a(24) =28224a(25) =31875a(26) =35828a(27) =40095a(28) =44688a(29) =49619