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Primes in A258774.
4

%I #19 Sep 08 2022 08:46:12

%S 3,13,43,157,73,241,157,211,601,601,421,601,2971,1483,8191,6163,3307,

%T 2971,6481,8191,28393,3907,28393,6481,8191,28393,37057,26407,12211,

%U 28393,31153,113233,19183,83233,113233,37057,28393,71023,22651,83233,37057,154057

%N Primes in A258774.

%C These primes are neither sorted nor uniqued. They are listed in the order found in A258774.

%H Robert Price, <a href="/A258776/b258776.txt">Table of n, a(n) for n = 1..2122</a>

%H OEIS Wiki, <a href="https://oeis.org/wiki/Cyclotomic Polynomials at x=n, n! and sigma(n)">Cyclotomic Polynomials at x=n, n! and sigma(n)</a>

%F a(n) = A258774(A258775(n)).

%t Select[Table[1 + DivisorSigma[1, n] + DivisorSigma[1, n]^2, {n, 1, 10000}], PrimeQ]

%t Select[Table[Cyclotomic[3, DivisorSigma[1, n]], {n, 1, 10000}], PrimeQ]

%o (Magma) [a: n in [1..300] | IsPrime(a) where a is 1+SumOfDivisors(n)+ SumOfDivisors(n)^2]; // _Vincenzo Librandi_, Jun 10 2015

%Y Cf. A000203, A258774, A258775.

%K nonn

%O 1,1

%A _Robert Price_, Jun 09 2015