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A067235 Numbers n such that phi(4n-1) = sigma(n). 1

%I

%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 n such that phi(4n-1) = sigma(n).

%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>

%o (PARI) for(n=1, 10^9, if(eulerphi(4*n-1)==sigma(n), print(n))) /* _Donovan Johnson_, Aug 18 2012 */

%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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Last modified November 29 18:41 EST 2021. Contains 349416 sequences. (Running on oeis4.)