A051204 Nonnegative numbers of the form x^2-2^y.

0, 1, 2, 3, 4, 5, 7, 8, 9, 12, 14, 15, 16, 17, 20, 21, 23, 24, 28, 32, 33, 34, 35, 36, 41, 45, 47, 48, 49, 56, 57, 60, 62, 63, 64, 65, 68, 73, 77, 79, 80, 84, 89, 92, 96, 97, 98, 99, 105, 112, 113, 117, 119, 120, 128, 129, 132, 136, 137, 140, 142, 143, 144, 153, 161, 164

Offset: 1

Author

David W. Wilson

Keywords

• nonn

Examples

			5 is in the sequence because 5 can be written as 3^2-2^2
		

Crossrefs

Cf. A051213.

Programs

Mathematica

max = 200; Clear[f]; f[m_] := f[m] = Select[Table[x^2 - 2^y, {y, 0, m}, {x, Floor[2^(y/2)], Ceiling[Sqrt[2^y + max]]}] // Flatten // Union, 0 <= # <= max &]; f[1]; f[m = 2]; While[f[m] != f[m/2], m = 2 m]; Print["m = ", m]; A051204 = f[m] (* Jean-François Alcover, May 13 2017 *)

Formula

{n: A247763(n) > 0 }. - R. J. Mathar, Jul 24 2022

Extensions

Corrected by Henry Bottomley, Jul 24 2000