9 times pentagonal numbers: 9*n*(3*n-1)/2.

Terms

a(0) =0a(1) =9a(2) =45a(3) =108a(4) =198a(5) =315a(6) =459a(7) =630a(8) =828a(9) =1053a(10) =1305a(11) =1584a(12) =1890a(13) =2223a(14) =2583a(15) =2970a(16) =3384a(17) =3825a(18) =4293a(19) =4788a(20) =5310a(21) =5859a(22) =6435a(23) =7038a(24) =7668a(25) =8325a(26) =9009a(27) =9720a(28) =10458a(29) =11223