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%I #18 Feb 06 2021 21:51:59
%S 10,15,25,27,29,31,33,36,37,44,54,64,69,78,81,82,88,102,106,110,121,
%T 142,148,177,183,192,211,212,240,270,272,274,280,314,332,337,338,344,
%U 367,381,384,404,412,421,429,434,460,463,467,490,502,511,519,523,530,551,559,584,586,588,614,624,628
%N Numbers k such that A067439(k) is prime.
%H Robert Israel, <a href="/A340731/b340731.txt">Table of n, a(n) for n = 1..10000</a>
%e a(3) = 25 is a term because A067439(25) = 83 is prime.
%p filter:= proc(n) local t,k;
%p isprime(add(`if`(igcd(n,k)=1, n mod k, 0),k=2..n-1))
%p end proc:
%p select(filter, [$1..1000]);
%o (PARI) isok(n) = isprime(sum(i=1, n-1, if(gcd(n, i)==1, n%i))); \\ _Michel Marcus_, Jan 18 2021
%Y Cf. A067439, A340736.
%K nonn
%O 1,1
%A _J. M. Bergot_ and _Robert Israel_, Jan 17 2021
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