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%I #10 May 15 2019 13:58:02
%S 3,7,10,11,16,19,22,23,25,27,31,34,43,46,49,58,59,71,79,82,83,94,100,
%T 103,106,118,121,131,139,142,163,166,178,191,199,202,208,211,214,223,
%U 226,251,262,271,274,298,311,331,334,346,358,359,379,382,383,394,419,443,454,463,466,478,479,484
%N Numbers k such that A023896(k) mod A000203(k) is prime.
%C Numbers k such that (k*A000010(k)/2) mod A000203(k) is prime.
%C The primes in the sequence are A092109.
%C The even semiprimes in the sequence are A112774.
%H Robert Israel, <a href="/A308169/b308169.txt">Table of n, a(n) for n = 1..10000</a>
%e a(3)=10 is in the sequence because A023896(10) mod A000203(10) = 20 mod 6 = 2, and 2 is prime.
%p select(n -> isprime((n*numtheory:-phi(n)/2) mod numtheory:-sigma(n)), [$2..1000]);
%o (PARI) isok(n) = isprime(n*eulerphi(n)/2 % sigma(n)); \\ _Michel Marcus_, May 15 2019
%Y Cf. A000010, A000203, A023896, A092109, A112774.
%K nonn
%O 1,1
%A _J. M. Bergot_ and _Robert Israel_, May 15 2019