A161140 Numbers which can be expressed as the product of numbers made of only twos.

1, 2, 4, 8, 16, 22, 32, 44, 64, 88, 128, 176, 222, 256, 352, 444, 484, 512, 704, 888, 968, 1024, 1408, 1776, 1936, 2048, 2222, 2816, 3552, 3872, 4096, 4444, 4884, 5632, 7104, 7744, 8192, 8888, 9768, 10648, 11264, 14208, 15488, 16384, 17776

Offset: 1

Author

Claudio Meller, Jun 03 2009

Keywords

• nonn
• base

Examples

			1 is the empty product; 44 is in the list because 44 = 2 * 22, 484 is in the list because 484 = 22 * 22.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A084034, A161141, A161142, A161143, A161144, A161145, A161146, A161147.

Programs

Maple

M:= 10^8:
S:= {1}:
for d from 1 to ilog10(M) do
  x:= 2/9*(10^d-1); T:= {}:
  for s in S do
    T:= T union {seq(s*x^i,i=1..floor(log[x](M/s)))};
  od;
  S:= S union T;
od:
sort(convert(S,list)); # Robert Israel, Dec 05 2024

Extensions

1 added by N. J. A. Sloane, Dec 04 2017