a(n) = n*(31*n + 1)/2.

Terms

a(0) =0a(1) =16a(2) =63a(3) =141a(4) =250a(5) =390a(6) =561a(7) =763a(8) =996a(9) =1260a(10) =1555a(11) =1881a(12) =2238a(13) =2626a(14) =3045a(15) =3495a(16) =3976a(17) =4488a(18) =5031a(19) =5605a(20) =6210a(21) =6846a(22) =7513a(23) =8211a(24) =8940a(25) =9700a(26) =10491a(27) =11313a(28) =12166a(29) =13050