Revert transform of (1 + x - 4x^2 - x^3)/(1 + 2x - 2x^2 - 2x^3).

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =20a(5) =72a(6) =270a(7) =1049a(8) =4176a(9) =16962a(10) =69990a(11) =292608a(12) =1236718a(13) =5275724a(14) =22685636a(15) =98225447a(16) =427888458a(17) =1873979814a(18) =8246535936a(19) =36444747110a(20) =161685649174a(21) =719819353928