Twice octagonal numbers: 2*n*(3*n-2).

Terms

a(0) =0a(1) =2a(2) =16a(3) =42a(4) =80a(5) =130a(6) =192a(7) =266a(8) =352a(9) =450a(10) =560a(11) =682a(12) =816a(13) =962a(14) =1120a(15) =1290a(16) =1472a(17) =1666a(18) =1872a(19) =2090a(20) =2320a(21) =2562a(22) =2816a(23) =3082a(24) =3360a(25) =3650a(26) =3952a(27) =4266a(28) =4592a(29) =4930