Least positive integer k for which 9^n divides k!.

Terms

a(0) =1a(1) =6a(2) =9a(3) =15a(4) =18a(5) =24a(6) =27a(7) =30a(8) =36a(9) =39a(10) =45a(11) =48a(12) =54a(13) =54a(14) =60a(15) =63a(16) =69a(17) =72a(18) =78a(19) =81a(20) =81a(21) =87a(22) =90a(23) =96a(24) =99a(25) =105a(26) =108a(27) =111a(28) =117a(29) =120