G.f. satisfies A(x)/A(x^2) = (1 + 9x + 9x^2 + 9x^3 + ...).

Terms

a(0) =1a(1) =9a(2) =18a(3) =90a(4) =108a(5) =252a(6) =342a(7) =1062a(8) =1170a(9) =2034a(10) =2286a(11) =4302a(12) =4644a(13) =7380a(14) =8442a(15) =16938a(16) =18108a(17) =27468a(18) =29502a(19) =45774a(20) =48060a(21) =66348a(22) =70650a(23) =105066a(24) =109710a(25) =146862a(26) =154242a(27) =213282a(28) =221724a(29) =289260