A258980 - OEIS

%I #22 Sep 08 2022 08:46:13

%S 5,2801,22621,30941,22621,637421,346201,346201,346201,2625641,837931,

%T 16007041,3835261,209102521,209102521,15018571,262209281,21700501,

%U 30397351,209102521,209102521,693025471,147753211,4244897281,1740422941,6903678241,2439903211

%N Primes in A258978.

%C These primes are neither sorted nor uniqued. They are listed in the order found in A258978.

%H Robert Price, <a href="/A258980/b258980.txt">Table of n, a(n) for n = 1..932</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) = A258978(A258979(n)).

%p with(numtheory): A258980:=n->`if`(isprime(1 + sigma(n) + sigma(n)^2 + sigma(n)^3 + sigma(n)^4), 1 + sigma(n) + sigma(n)^2 + sigma(n)^3 + sigma(n)^4, NULL): seq(A258980(n), n=1..300); # _Wesley Ivan Hurt_, Jul 09 2015

%t Select[Table[1 + DivisorSigma[1, n] + DivisorSigma[1, n]^2 + DivisorSigma[1, n]^3 + DivisorSigma[1, n]^4, {n, 10000}], PrimeQ]

%t Select[Table[Cyclotomic[5, DivisorSigma[1, n]], {n, 10000}], PrimeQ]

%o (Magma) [m: n in [1..200] | IsPrime(m) where m is (1 + DivisorSigma(1, n) + DivisorSigma(1, n)^2 + DivisorSigma(1, n)^3 + DivisorSigma(1, n)^4)]; // _Vincenzo Librandi_, Jun 16 2015

%Y Cf. A000203, A258978, A258979.

%K nonn

%O 1,1

%A _Robert Price_, Jun 15 2015