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Revision History for A070763

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A070763

Numbers n such that sigma(n) is a power of prime (of the form p^a, p prime, a>=1).
(history; published version)

#12 by Bruno Berselli at Thu Feb 09 06:12:32 EST 2017

STATUS

proposed

approved

#11 by Michel Marcus at Wed Feb 08 23:37:31 EST 2017

STATUS

editing

proposed

#10 by Michel Marcus at Wed Feb 08 23:37:09 EST 2017

CROSSREFS

Cf. A071114.

#9 by Michel Marcus at Wed Feb 08 23:36:57 EST 2017

EXAMPLE

sigma(57337)=2^16 hence 57337 is in the sequence.

STATUS

proposed

editing

#8 by Ivan Neretin at Wed Feb 08 17:08:08 EST 2017

STATUS

editing

proposed

#7 by Ivan Neretin at Wed Feb 08 17:07:02 EST 2017

COMMENTS

Contains all Mersenne primes (A000668) and squarefree products thereof (A046528 except 1). - Ivan Neretin, Feb 08 2017

LINKS

Ivan Neretin, <a href="/A070763/b070763.txt">Table of n, a(n) for n = 1..10000</a>

MATHEMATICA

Select[Range[100000], PrimePowerQ[DivisorSigma[1, #]] &] (* Ivan Neretin, Feb 08 2017 *)

CROSSREFS

Cf. A071114

STATUS

approved

editing

#6 by Russ Cox at Fri Mar 30 18:38:59 EDT 2012

AUTHOR

_Benoit Cloitre (benoit7848c(AT)orange.fr), _, May 14 2002

Discussion

Fri Mar 30

18:38

OEIS Server: https://oeis.org/edit/global/216

#5 by N. J. A. Sloane at Sun Jun 29 03:00:00 EDT 2008

KEYWORD

easy,nonn,new

AUTHOR

Benoit Cloitre (abmtbenoit7848c(AT)wanadooorange.fr), May 14 2002

#4 by N. J. A. Sloane at Wed Sep 21 03:00:00 EDT 2005

KEYWORD

easy,nonn,new

AUTHOR

Benoit Cloitre (abcloitreabmt(AT)modulonetwanadoo.fr), May 14 2002

#3 by N. J. A. Sloane at Tue Jul 19 03:00:00 EDT 2005

KEYWORD

easy,nonn,new

AUTHOR

Benoit Cloitre (abcloitre(AT)wanadoomodulonet.fr), May 14 2002