A051220 Numbers of the form 9^x-y^2 >= 0.

0, 1, 5, 8, 9, 17, 32, 45, 53, 56, 65, 72, 77, 80, 81, 104, 153, 161, 200, 245, 288, 320, 329, 368, 405, 440, 473, 477, 485, 504, 533, 560, 585, 608, 629, 632, 648, 665, 680, 693, 704, 713, 720, 725, 728, 729, 785, 936, 968, 1085, 1232, 1377, 1449, 1457, 1520

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Programs

Mathematica

max = 2000; Clear[f]; f[m_] := f[m] = Select[Table[9^x - y^2, {x, 0, m}, {y, 0, Ceiling[9^(x/2)]}] // Flatten // Union, 0 <= # <= max &]; f[1]; f[m = 2]; While[f[m] != f[m - 1], m++]; Print["m = ", m]; A051219 = f[m] (* Jean-François Alcover, May 14 2017 *)