A051214 Numbers of the form 3^x-y^2 >= 0.

0, 1, 2, 3, 5, 8, 9, 11, 17, 18, 23, 26, 27, 32, 45, 47, 53, 56, 65, 71, 72, 74, 77, 80, 81, 83, 99, 104, 122, 143, 153, 161, 162, 179, 194, 200, 207, 218, 227, 234, 239, 242, 243, 245, 251, 288, 320, 329, 338, 362, 368, 405, 423, 440, 473, 477, 485, 504, 506, 533

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1331

Crossrefs

Cf. A201124.

Programs

Mathematica

max = 1000; Clear[f]; f[m_] := f[m] = Select[Table[3^x - y^2, {x, 0, m}, {y, 0, Ceiling[3^(x/2)]}] // Flatten // Union, 0 <= # <= max &]; f[1]; f[m = 2]; While[f[m] != f[m - 1], m++]; Print["m = ", m]; A051214 = f[m] (* Jean-François Alcover, May 14 2017 *)