A054157 Number of positive integers <= 2^n of form 2 x^2 + 7 y^2.

0, 1, 1, 3, 5, 10, 17, 33, 58, 109, 202, 379, 720, 1369, 2618, 5031, 9701, 18766, 36387, 70688, 137572, 268208, 523581, 1023425, 2002829, 3923400, 7692930, 15096706, 29649082, 58270386, 114596178, 225503077, 443996993, 874648723, 1723849033