A054166 Number of positive integers <= 2^n of form 3 x^2 + 9 y^2.

0, 0, 1, 1, 3, 5, 10, 17, 32, 56, 106, 195, 365, 691, 1308, 2495, 4773, 9174, 17671, 34144, 66131, 128330, 249482, 485761, 947206, 1849299, 3614605, 7072464, 13851148, 27150649, 53262111, 104562496, 205412762, 403786919, 794202162