

A181705


Numbers of the form 2^(t1)*(2^t9), where 2^t9 is prime.


1




OFFSET

1,1


COMMENTS

All entries are nearperfect numbers (A181595).
(Proof: Let m=2^(t1)*(2^t9) be the entry. By the multiplicative property of the sigmafunction, sigma(m)=(2^t1)*(2^t8).
The abundance sigma(m)2*m is therefore 8, and since all t involved are >=4, 8 is a divisor of m because 8 divides 2^(t1).)


LINKS

Table of n, a(n) for n=1..8.


MATHEMATICA

2^(#1) (2^#9)&/@Select[Range[3, 130], PrimeQ[2^#9]&] (* Harvey P. Dale, Oct 24 2011 *)


CROSSREFS

Cf. A059610, A181595, A181701, A000396, A181703, A181704
Sequence in context: A003783 A088833 A181598 * A219826 A075283 A205313
Adjacent sequences: A181702 A181703 A181704 * A181706 A181707 A181708


KEYWORD

nonn


AUTHOR

Vladimir Shevelev, Nov 06 2010


EXTENSIONS

Edited by R. J. Mathar, Sep 12 2011


STATUS

approved



