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%I #14 Aug 22 2015 17:20:44
%S 1,3,5,10,11,23,33,46,65,77,123,136,221,371,383,423,483,513,545,670,
%T 753,1643,2033,3838,3885,4533,4798,5177,7463,7739,8201,8985,9010,9393,
%U 12256,13144,14104,17110,17147,17663,18695,19817,21119,23038,24695
%N Numbers n such that phi(2n-1) = sigma(n).
%H Donovan Johnson, <a href="/A067230/b067230.txt">Table of n, a(n) for n = 1..1000</a>
%t Select[Range[25000],EulerPhi[2#-1]==DivisorSigma[1,#]&] (* _Harvey P. Dale_, Aug 22 2015 *)
%o (PARI) isok(n) = eulerphi(2*n-1) == sigma(n); \\ _Michel Marcus_, Nov 21 2013
%Y Cf. A000010, A000203, A067229.
%K nonn
%O 1,2
%A _Benoit Cloitre_, Feb 20 2002
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