A110911 Positive integers that can be expressed in the form (a*2^a)/(b*2^b) where a and b are positive integers.

1, 3, 4, 5, 6, 8, 9, 10, 11, 12, 14, 16, 17, 18, 20, 24, 32, 33, 34, 36, 37, 40, 42, 48, 52, 64, 65, 66, 67, 68, 70, 72, 76, 80, 88, 96, 112, 128, 129, 130, 132, 135, 136, 142, 144, 156, 160, 184, 192, 240, 256, 257, 258, 260, 264, 272, 288, 320, 352, 384, 448, 512, 513

Offset

1,2

Comments

Odd values > 1 are of the form 2^n + odd divisor of n.

Links

Table of n, a(n) for n=1..63.

Example

6 is included because 6 = (6*2^6)/(4*2^4)
12 is a member because 12 = (3*2^3)/(1*2^1) = (9*2^9)/(6*2^6). Entries which are generated in two or more different ways are 1,12,20,32,48,72,80,112,160,192,256,576,768,..., . - Robert G. Wilson v, May 10 2006

Mathematica

lst = {1}; Do[ If[ (Log[10, a] + a*Log[10, 2]) - (Log[10, b] + b*Log[10, 2]) < 3 && IntegerQ[(a*2^a)/(b*2^b)], AppendTo[lst, (a*2^a)/(b*2^b)]; Print[(a*2^a)/(b*2^b)]], {a, 4620}, {b, Max[1, a - 9(* =Log[2, 10^3] *)], a-1}]; lst (* Robert G. Wilson v, May 10 2006 *)

Crossrefs

Sequence in context: A184427 A001965 A039178 * A103202 A188040 A099352

Adjacent sequences: A110908 A110909 A110910 * A110912 A110913 A110914

Keyword

nonn

Author

Sam Handler (sam_5_5_5_0(AT)yahoo.com), Oct 09 2005

Extensions

More terms from David W. Wilson

Status

approved