A051209 Nonnegative numbers of the form x^2-7^y.

0, 2, 3, 8, 9, 15, 18, 24, 29, 32, 35, 42, 48, 51, 57, 63, 72, 74, 80, 93, 95, 98, 99, 114, 120, 137, 141, 143, 147, 162, 168, 176, 186, 189, 195, 200, 207, 218, 224, 233, 240, 249, 255, 275, 282, 288, 303, 312, 317, 323, 333, 351, 354, 360, 386, 392, 393, 399

Offset

1,2

Links

Table of n, a(n) for n=1..58.

Mathematica

max = 400; Clear[f]; f[m_] := f[m] = Select[Table[x^2 - 7^y, {y, 0, m}, {x, Floor[7^(y/2)], Ceiling[Sqrt[7^y + max]]}] // Flatten // Union, 0 <= # <= max &]; f[1]; f[m = 2]; While[f[m] != f[m - 1], m++]; Print["m = ", m]; A051209 = f[m] (* Jean-François Alcover, May 14 2017 *)

Crossrefs

Sequence in context: A054462 A101471 A137471 * A332481 A331821 A093765

Adjacent sequences: A051206 A051207 A051208 * A051210 A051211 A051212

Keyword

nonn

Author

David W. Wilson

Status

approved