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%I #15 May 09 2022 08:36:27
%S 660,744,4216,6460,10780,11880,14688,27820,32524,37464,40120,59964,
%T 87124,110770,120934,125764,184264,190564,194584,210324,264280,269514,
%U 295144,297388,298840,314974,379204,384750,396256,396520,406296,444244,473524,597480
%N Numbers k such that phi(4k-1) = sigma(k).
%C Are there any odd terms in the sequence?
%H Donovan Johnson, <a href="/A067235/b067235.txt">Table of n, a(n) for n = 1..1000</a>
%t Select[Range[600000], EulerPhi[4*# - 1] == DivisorSigma[1, #] &] (* _Amiram Eldar_, May 09 2022 *)
%o (PARI) for(n=1, 10^9, if(eulerphi(4*n-1)==sigma(n), print(n))) /* _Donovan Johnson_, Aug 18 2012 */
%Y Cf. A000010, A000203, A067224, A067226.
%K nonn
%O 1,1
%A _Benoit Cloitre_, Feb 20 2002
%E More terms from _Harvey P. Dale_, Feb 26 2002
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