A049137 Revert transform of (1 - x - 4x^2 + x^3)/(1 - 4x^2 - 2x^3).

1, 1, 2, 6, 22, 88, 370, 1607, 7150, 32418, 149246, 695840, 3278942, 15591708, 74721660, 360540041, 1750069638, 8539926158, 41869742140, 206149706634, 1018875856490, 5053136206216, 25140141786040, 125436643981858