Position of n-th 9 in A031298.

Terms

a(0) =9a(1) =28a(2) =48a(3) =68a(4) =88a(5) =108a(6) =128a(7) =148a(8) =168a(9) =171a(10) =173a(11) =175a(12) =177a(13) =179a(14) =181a(15) =183a(16) =185a(17) =187a(18) =188a(19) =189a(20) =217a(21) =247a(22) =277a(23) =307a(24) =337a(25) =367a(26) =397a(27) =427a(28) =457a(29) =461