The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A067536

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A067536

Numbers k such that phi(k*(k+1)*(k+2)/3)/phi(k) is not an integer where phi(k) is the Euler totient function A000010(k).
(history; published version)

#13 by Michel Marcus at Sun Mar 01 04:45:19 EST 2020

STATUS

reviewed

approved

#12 by Joerg Arndt at Sun Mar 01 04:29:07 EST 2020

STATUS

proposed

reviewed

#11 by Amiram Eldar at Sun Mar 01 04:25:47 EST 2020

STATUS

editing

proposed

#10 by Amiram Eldar at Sun Mar 01 03:54:16 EST 2020

NAME

Numbers n k such that phi(nk*(nk+1)*(nk+2)/3)/phi(nk) is not an integer where phi(nk) is the Euler totient function A000010(nk).

MATHEMATICA

Select[Range[2000], ! Divisible[EulerPhi[#*(# + 1)*(# + 2)/3], EulerPhi[#]] &] (* Amiram Eldar, Mar 01 2020 *)

CROSSREFS

Cf. A000010, A007290.

#9 by Amiram Eldar at Sun Mar 01 03:52:31 EST 2020

LINKS

Amiram Eldar, <a href="/A067536/b067536.txt">Table of n, a(n) for n = 1..10000</a>

STATUS

approved

editing

#8 by Charles R Greathouse IV at Tue Mar 05 00:53:33 EST 2013

STATUS

editing

approved

#7 by Charles R Greathouse IV at Tue Mar 05 00:53:29 EST 2013

PROG

(PARI) is(n)=eulerphi(n*(n+1)*(n+2)/3)%eulerphi(n) \\ Charles R Greathouse IV, Mar 05 2013

STATUS

approved

editing

#6 by Russ Cox at Fri Mar 30 18:38:51 EDT 2012

AUTHOR

_Benoit Cloitre (benoit7848c(AT)orange.fr), _, Jan 28 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

nonn,new

nonn

AUTHOR

Benoit Cloitre (abmtbenoit7848c(AT)wanadooorange.fr), Jan 28 2002

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

KEYWORD

nonn,new

nonn

AUTHOR

Benoit Cloitre (abcloitreabmt(AT)modulonetwanadoo.fr), Jan 28 2002