a(n) = position of n^3 + 9 in A003072.

Terms

a(0) =2a(1) =3a(2) =6a(3) =11a(4) =19a(5) =31a(6) =47a(7) =68a(8) =96a(9) =128a(10) =168a(11) =214a(12) =266a(13) =328a(14) =402a(15) =487a(16) =571a(17) =672a(18) =793a(19) =916a(20) =1061a(21) =1218a(22) =1391a(23) =1570a(24) =1770a(25) =1986a(26) =2211a(27) =2462a(28) =2719a(29) =3017