A054159 Number of positive integers <= 2^n of form 2 x^2 + 9 y^2.

0, 1, 1, 2, 4, 8, 15, 27, 51, 93, 174, 329, 620, 1177, 2250, 4308, 8286, 15961, 30871, 59792, 116083, 225754, 439666, 857554, 1674630, 3273944, 6407147, 12550615, 24605525, 48277287, 94790704, 186242926, 366153007, 720274117, 1417640576