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

Terms

a(0) =0a(1) =3a(2) =14a(3) =33a(4) =60a(5) =95a(6) =138a(7) =189a(8) =248a(9) =315a(10) =390a(11) =473a(12) =564a(13) =663a(14) =770a(15) =885a(16) =1008a(17) =1139a(18) =1278a(19) =1425a(20) =1580a(21) =1743a(22) =1914a(23) =2093a(24) =2280a(25) =2475a(26) =2678a(27) =2889a(28) =3108a(29) =3335