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`%I #7 Mar 18 2021 22:59:20
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`%S 5,6,7,14,18,24,29,34,39,41,47,53,77,114,119,148,150,159,176,188,189,
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`%T 190,191,205,215,217,218,241,268,288,312,314,331,334,339,342,346,352,
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`%U 364,367,387,390,402,418,429,438,439,440,446,449,480,493,494,500,504,510,521,523,546,549,553,561,580
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`%N Numbers k such that A340180(k) is prime.
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`%H Robert Israel, <a href="/A342630/b342630.txt">Table of n, a(n) for n = 1..5000</a>
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`%e a(4) = 14 is a term because A340180(14) = 23 is prime.
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`%p f:= proc(n) local s,k;
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`%p s:= numtheory:-sigma(n);
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`%p add(`if`(igcd(n,k)=1, s mod k, 0),k=1..n-1);
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`%p end proc:
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`%p select(t -> isprime(f(t)), [$1..1000]);
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`%Y Cf. A340180.
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`%K nonn
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`%O 1,1
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`%A _J. M. Bergot_ and _Robert Israel_, Mar 17 2021
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