9 times octagonal numbers: a(n) = 9*n*(3*n-2).

Terms

a(0) =0a(1) =9a(2) =72a(3) =189a(4) =360a(5) =585a(6) =864a(7) =1197a(8) =1584a(9) =2025a(10) =2520a(11) =3069a(12) =3672a(13) =4329a(14) =5040a(15) =5805a(16) =6624a(17) =7497a(18) =8424a(19) =9405a(20) =10440a(21) =11529a(22) =12672a(23) =13869a(24) =15120a(25) =16425a(26) =17784a(27) =19197a(28) =20664a(29) =22185