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%I #8 Jul 15 2021 06:31:50
%S 1,4,15,33,35,36,50,55,57,64,65,75,77,85,87,93,98,115,119,129,133,143,
%T 155,159,185,187,189,205,213,215,217,219,242,243,247,253,265,287,295,
%U 303,309,323,324,327,339,345,365,385,393,395,407,425,427,453,469,493
%N Numbers k such that k + phi(k) + sigma(k) is a prime.
%H Harvey P. Dale, <a href="/A116035/b116035.txt">Table of n, a(n) for n = 1..1000</a>
%e 205 + phi(205) + sigma(205) = 617 (prime).
%t Select[Range[500],PrimeQ[#+EulerPhi[#]+DivisorSigma[1,#]]&] (* _Harvey P. Dale_, Nov 09 2014 *)
%Y Cf. A078762, A068080.
%K nonn
%O 1,2
%A _Giovanni Resta_, Feb 13 2006
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