|
%I #17 Sep 09 2019 01:23:28
%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 k such that phi(k) | sigma(k + 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 inserted by _Ivan Neretin_, Feb 05 2017
|
