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%I #14 Oct 09 2020 15:31:41
%S 7,1093,55987,5229043,8108731,917087137,47446779661,917087137,
%T 4201025641,31401724537,141276239497,3092313043,47446779661,
%U 31401724537,141276239497,654022685443,141276239497,141276239497,265462278481,47446779661,100343116693,4033516174507
%N Primes of the form: 1 + sigma(n) + sigma(n)^2 + sigma(n)^3 + sigma(n)^4 + sigma(n)^5 + sigma(n)^6.
%C These primes are neither sorted nor uniqued. They are listed in the order found in A259251.
%H Robert Price, <a href="/A259253/b259253.txt">Table of n, a(n) for n = 1..885</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) = A259251(A259252(n)).
%p with(numtheory): A259253:=n->`if`(isprime(1 + sigma(n) + sigma(n)^2 + sigma(n)^3 + sigma(n)^4+sigma(n)^5+sigma(n)^6), 1 + sigma(n) + sigma(n)^2 + sigma(n)^3 + sigma(n)^4 + sigma(n)^5 + sigma(n)^6, NULL): seq(A259253(n), n=1..100); # _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 + DivisorSigma[1, n]^5 + DivisorSigma[1, n]^6, {n, 10000}], PrimeQ]
%t Select[Table[Cyclotomic[7, DivisorSigma[1, n]], {n, 10000}], PrimeQ]
%t Select[Table[Total[DivisorSigma[1,n]^Range[0,6]],{n,80}],PrimeQ] (* _Harvey P. Dale_, Oct 09 2020 *)
%Y Cf. A000203, A259251, A259252.
%K easy,nonn
%O 1,1
%A _Robert Price_, Jun 22 2015
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