A051218 Numbers of the form 7^x-y^2 >= 0.

0, 1, 3, 6, 7, 13, 19, 24, 33, 40, 45, 48, 49, 54, 87, 97, 118, 147, 166, 174, 192, 199, 222, 243, 262, 279, 285, 294, 307, 318, 327, 334, 339, 342, 343, 376, 423, 465, 552, 637, 678, 685, 720, 801, 880, 894, 931, 957, 1032, 1105, 1176, 1182, 1245, 1312

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Crossrefs

Cf. A201123.

Programs

Mathematica

max = 2000; Clear[f]; f[m_] := f[m] = Select[Table[7^x - y^2, {x, 0, m}, {y, 0, Ceiling[7^(x/2)]}] // Flatten // Union, 0 <= # <= max &]; f[1]; f[m = 2]; While[f[m] != f[m - 1], m++]; Print["m = ", m]; A051218 = f[m] (* Jean-François Alcover, May 14 2017 *)