A111261 Numbers of the form (m/n)^(m-n) with m >=n.

1, 2, 4, 8, 9, 16, 32, 64, 81, 128, 256, 512, 625, 729, 1024, 2048, 4096, 6561, 7776, 8192, 16384, 32768, 59049, 65536, 117649, 131072, 262144, 390625, 524288, 531441, 1048576, 2097152, 4194304, 4782969, 8388608, 16777216, 33554432, 43046721

Offset

1,2

Comments

All powers of 2 are present, even powers of 3, fourth powers of 5, etc. - Robert G. Wilson v

Links

Table of n, a(n) for n=1..38.

Example

The 10th element is a=128 with m = 14 and n =7 because 128 =(14/7)^(14-7).

Maple

a:=proc(N) local a, m, n; for m from 1 to N do for n from 1 to m do a:=(m/n)^(m-n); if(floor(a)=a) then print(a) fi; od; od; end: # convert into set # sort set

Mathematica

Take[ Select[ Union[ Flatten[ Table[(m/n)^(m - n), {m, 52}, {n, m}]]], IntegerQ[ # ] &], 40] (* Robert G. Wilson v *)

Crossrefs

Sequence in context: A113570 A065391 A161792 * A276773 A294441 A246347

Adjacent sequences: A111258 A111259 A111260 * A111262 A111263 A111264

Keyword

nonn

Author

Paolo P. Lava and Giorgio Balzarotti, Nov 12 2005

Extensions

Corrected and extended by Robert G. Wilson v, Nov 14 2005

Status

approved