The On-Line Encyclopedia of Integer Sequences (OEIS)

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A055163

(n - Phi(n)) | Sigma(n) for composite n.
(history; published version)

#8 by Harvey P. Dale at Mon May 16 14:16:58 EDT 2016

STATUS

editing

approved

#7 by Harvey P. Dale at Mon May 16 14:16:53 EDT 2016

LINKS

Harvey P. Dale, <a href="/A055163/b055163.txt">Table of n, a(n) for n = 1..1000</a>

STATUS

approved

editing

#6 by Harvey P. Dale at Mon May 16 14:15:45 EDT 2016

STATUS

editing

approved

#5 by Harvey P. Dale at Mon May 16 14:15:41 EDT 2016

MATHEMATICA

Select[Range[500], CompositeQ[#]&&Divisible[DivisorSigma[1, #], #-EulerPhi[ #]]&] (* Harvey P. Dale, May 16 2016 *)

STATUS

approved

editing

#4 by Russ Cox at Fri Mar 30 17:30:20 EDT 2012

AUTHOR

_Robert G. Wilson v (rgwv(AT)rgwv.com), _, Jun 30 2000

Discussion

Fri Mar 30

17:30

OEIS Server: https://oeis.org/edit/global/156

#3 by N. J. A. Sloane at Fri Feb 24 03:00:00 EST 2006

MATHEMATICA

Do[ If[ !PrimeQ[ n ], If[ Mod[ DivisorSigma[ 1, n ], n-EulerPhi[ n ] ] == 0, Print[ n ] ], {n, 1, 500} ]

KEYWORD

easy,nonn,new

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

MATHEMATICA

Do[ If[ !PrimeQ[ n ], If[ Mod[ DivisorSigma[ 1, n ], n-EulerPhi[ n ] ] = = 0, Print[ n ] ], {n, 1, 500} ]

KEYWORD

easy,nonn,new

AUTHOR

Robert G. Wilson v (RGWv@kspaintrgwv(AT)rgwv.com), Jun 30 2000

#1 by N. J. A. Sloane at Sat Jul 22 03:00:00 EDT 2000

NAME

(n - Phi(n)) | Sigma(n) for composite n.

DATA

6, 10, 14, 22, 26, 34, 38, 46, 58, 62, 74, 82, 86, 94, 99, 106, 118, 122, 134, 142, 146, 158, 166, 168, 178, 187, 194, 202, 206, 214, 218, 226, 254, 262, 274, 278, 298, 302, 314, 326, 334, 346, 358, 362, 382, 386, 394, 398, 422, 446, 454, 458, 466, 478, 482

OFFSET

1,1

MATHEMATICA

Do[ If[ !PrimeQ[ n ], If[ Mod[ DivisorSigma[ 1, n ], n-EulerPhi[ n ] ] = = 0, Print[ n ] ], {n, 1, 500} ]

KEYWORD

easy,nonn

AUTHOR

Robert G. Wilson v (RGWv@kspaint.com), Jun 30 2000

STATUS

approved