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A015834 Numbers n such that phi(n) | sigma(n + 1). 6

%I

%S 1,2,4,5,6,9,10,13,14,20,21,30,32,34,43,45,54,55,65,68,70,104,109,114,

%T 129,132,140,151,153,160,176,183,203,234,245,252,279,314,340,370,407,

%U 434,441,539,550,580,589,620,635,644,741,765,798,806,845,860,883

%N Numbers n such that phi(n) | sigma(n + 1).

%H Ivan Neretin, <a href="/A015834/b015834.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Range[3000], Divisible[DivisorSigma[1, 1 + #], EulerPhi[#]] &] (* David Nacin, Mar 03 2012 *)

%o (PARI) is(n)=!(sigma(n+1)%eulerphi(n)) \\ _Charles R Greathouse IV_, Sep 25 2012

%K nonn

%O 1,2

%A _Robert G. Wilson v_

%E a(1) = 1 added by _Ivan Neretin_, Feb 05 2017

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Last modified May 19 04:06 EDT 2019. Contains 323377 sequences. (Running on oeis4.)