A172148 Number of subsets S of {1,2,3,...,n} with the property that if x is a member of S then at least one of x/2 and 2x is also a member of S

1, 2, 2, 4, 4, 8, 8, 14, 14, 28, 28, 56, 56, 112, 112, 192, 192, 384, 384, 768, 768, 1536, 1536, 2688, 2688, 5376, 5376, 10752, 10752, 21504, 21504, 37632, 37632, 75264, 75264, 150528, 150528, 301056, 301056, 526848, 526848, 1053696, 1053696, 2107392, 2107392

Offset

1,2

Comments

For the terms a(1) through a(25) is it seen that if n is odd then a(n)=a(n-1); also that if n is not a multiple of 4 then a(2n)=2a(2n-2). Does this behavior continue?

Links

David A. Corneth, Table of n, a(n) for n = 1..6993 (terms < 10^1000)

Crossrefs

Cf. A172020.

Sequence in context: A116931 A206558 A145810 * A205478 A262966 A034397

Adjacent sequences: A172145 A172146 A172147 * A172149 A172150 A172151

Keyword

nonn

Author

John W. Layman, Jan 26 2010

Extensions

a(26)-a(45) from Fausto A. C. Cariboni, Oct 03 2020

Status

approved