A049141 Revert transform of (1 + x - 4x^2 - x^3)/(1 + 2x - 2x^2 - 2x^3).

1, 1, 2, 6, 20, 72, 270, 1049, 4176, 16962, 69990, 292608, 1236718, 5275724, 22685636, 98225447, 427888458, 1873979814, 8246535936, 36444747110, 161685649174, 719819353928, 3214805630688, 14399464322254, 64668729869542