This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A259253 #14 Oct 09 2020 15:31:41
%S A259253 7,1093,55987,5229043,8108731,917087137,47446779661,917087137,
%T A259253 4201025641,31401724537,141276239497,3092313043,47446779661,
%U A259253 31401724537,141276239497,654022685443,141276239497,141276239497,265462278481,47446779661,100343116693,4033516174507
%N A259253 Primes of the form: 1 + sigma(n) + sigma(n)^2 + sigma(n)^3 + sigma(n)^4 + sigma(n)^5 + sigma(n)^6.
%C A259253 These primes are neither sorted nor uniqued. They are listed in the order found in A259251.
%H A259253 Robert Price, <a href="/A259253/b259253.txt">Table of n, a(n) for n = 1..885</a>
%H A259253 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 A259253 a(n) = A259251(A259252(n)).
%p A259253 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 A259253 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 A259253 Select[Table[Cyclotomic[7, DivisorSigma[1, n]], {n, 10000}], PrimeQ]
%t A259253 Select[Table[Total[DivisorSigma[1,n]^Range[0,6]],{n,80}],PrimeQ] (* _Harvey P. Dale_, Oct 09 2020 *)
%Y A259253 Cf. A000203, A259251, A259252.
%K A259253 easy,nonn
%O A259253 1,1
%A A259253 _Robert Price_, Jun 22 2015