A051215 Numbers of the form 4^x-y^2 >= 0.

0, 1, 3, 4, 7, 12, 15, 16, 28, 31, 39, 48, 55, 60, 63, 64, 87, 112, 124, 127, 135, 156, 175, 183, 192, 207, 220, 231, 240, 247, 252, 255, 256, 295, 348, 375, 399, 448, 495, 496, 508, 511, 540, 583, 615, 624, 663, 700, 732, 735, 759, 768, 799, 828, 847, 855, 880

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Programs

Mathematica

max = 1000; Clear[f]; f[m_] := f[m] = Select[Table[4^x - y^2, {x, 0, m}, {y, 0, Ceiling[4^(x/2)]}] // Flatten // Union, 0 <= # <= max &]; f[1]; f[m = 2]; While[f[m] != f[m - 1], m++]; Print["m = ", m]; A051215 = f[m] (* Jean-François Alcover, May 14 2017 *)