The On-Line Encyclopedia of Integer Sequences (OEIS)

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A067879

Numbers n such that sigma(n)=phi(n*omega(n)+1).
(history; published version)

#8 by Harvey P. Dale at Sat Jul 08 09:48:27 EDT 2017

STATUS

editing

approved

#7 by Harvey P. Dale at Sat Jul 08 09:48:23 EDT 2017

COMMENTS

"Omega(n)" in the definition means the number of distinct prime factors of n, counted without multiplicity. This is implemented in Mathematica as PrimeNu[n] rather than as PrimeOmega[n]. - Harvey P. Dale, Jul 08 2017

LINKS

Harvey P. Dale, <a href="/A067879/b067879.txt">Table of n, a(n) for n = 1..200</a>

MATHEMATICA

Select[Range[13000], DivisorSigma[1, #]==EulerPhi[#*PrimeNu[#]+1]&] (* Harvey P. Dale, Jul 08 2017 *)

STATUS

approved

editing

#6 by Russ Cox at Fri Mar 30 18:38:52 EDT 2012

AUTHOR

_Benoit Cloitre (benoit7848c(AT)orange.fr), _, Mar 02 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), Mar 02 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), Mar 02 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), Mar 02 2002

#2 by N. J. A. Sloane at Sat Jun 12 03:00:00 EDT 2004

NAME

Numbers n such that sigma(n)=phi(n*omega(n)+1).

KEYWORD

easy,nonn,new

#1 by N. J. A. Sloane at Fri May 16 03:00:00 EDT 2003

NAME

n such that sigma(n)=phi(n*omega(n)+1).

DATA

1, 6, 30, 38, 55, 85, 87, 188, 236, 264, 445, 451, 618, 655, 672, 715, 717, 897, 913, 1221, 1265, 1357, 1824, 2095, 2515, 2765, 3009, 3247, 3471, 3605, 3741, 4088, 4117, 4237, 5071, 6747, 7195, 7689, 7701, 8120, 10885, 11577, 12128, 12245, 12549

OFFSET

1,2

KEYWORD

easy,nonn

AUTHOR

Benoit Cloitre (abcloitre(AT)wanadoo.fr), Mar 02 2002

STATUS

approved