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

Terms

a(0) =0a(1) =6a(2) =20a(3) =42a(4) =72a(5) =110a(6) =156a(7) =210a(8) =272a(9) =342a(10) =420a(11) =506a(12) =600a(13) =702a(14) =812a(15) =930a(16) =1056a(17) =1190a(18) =1332a(19) =1482a(20) =1640a(21) =1806a(22) =1980a(23) =2162a(24) =2352a(25) =2550a(26) =2756a(27) =2970a(28) =3192a(29) =3422