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 A259184 #16 Jul 10 2015 00:36:54
%S A259184 1,7,13,43,31,133,57,211,157,307,133,757,183,553,553,931,307,1483,381,
%T A259184 1723,993,1261,553,3541,931,1723,1561,3081,871,5113,993,3907,2257,
%U A259184 2863,2257,8191,1407,3541,3081,8011,1723,9121,1893,6973,6007,5113,2257,15253
%N A259184 a(n) = 1 - sigma(n) + sigma(n)^2.
%H A259184 Robert Price, <a href="/A259184/b259184.txt">Table of n, a(n) for n = 1..10000</a>
%H A259184 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 A259184 a(n) = 1 - A000203(n) + A000203(n)^2.
%F A259184 a(n) = 1 - A000203(n) + A072861(n). - _Omar E. Pol_, Jun 20 2015
%F A259184 a(n) = A002061(A000203(n)). - _Michel Marcus_, Jun 25 2015
%p A259184 with(numtheory): A259184:=n->1-sigma(n)+sigma(n)^2: seq(A259184(n), n=1..100); # _Wesley Ivan Hurt_, Jul 09 2015
%t A259184 Table[1 - DivisorSigma[1, n] + DivisorSigma[1, n]^2, {n, 10000}]
%t A259184 Table[Cyclotomic[6, DivisorSigma[1, n]], {n, 10000}]
%o A259184 (PARI) a(n) = polcyclo(6, sigma(n)); \\ _Michel Marcus_, Jun 25 2015
%Y A259184 Cf. A000203 (sum of divisors of n).
%Y A259184 Cf. A259185 (indices of primes in this sequence), A259186 (corresponding primes).
%K A259184 easy,nonn
%O A259184 1,2
%A A259184 _Robert Price_, Jun 20 2015