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 A015771 #12 Nov 02 2019 06:42:43
%S A015771 1,2,3,6,12,14,15,30,35,42,56,70,78,105,140,168,190,210,248,264,270,
%T A015771 357,418,420,570,594,616,630,714,744,749,812,840,910,1045,1240,1254,
%U A015771 1485,1498,1672,1848,2090,2214,2247,2376,2436,2568,2580,2730
%N A015771 Numbers k such that phi(k) | sigma_13(k).
%C A015771 sigma_13(n) is the sum of the 13th powers of the divisors of n.
%H A015771 Amiram Eldar, <a href="/A015771/b015771.txt">Table of n, a(n) for n = 1..10000</a>
%F A015771 {n: A000010(n) | A013961(n)}. - _R. J. Mathar_, Sep 21 2017
%p A015771 with(numtheory); a := []: for n from 1 to 3000 do if sigma[13](n) mod phi(n) = 0 then a := [op(a), n]; fi; od: a;
%t A015771 Select[Range[3000], Divisible[DivisorSigma[13, #], EulerPhi[#]] &] (* _Amiram Eldar_, Nov 02 2019 *)
%Y A015771 Cf. A000010, A013961.
%Y A015771 Cf. A020492, A015759, A015761, A015762, A015763, A015764, A015765, A015766, A015767, A015768, A015769, A015770, A015773, A015774, A094470.
%K A015771 nonn
%O A015771 1,2
%A A015771 _Robert G. Wilson v_
%E A015771 Offset corrected by _Amiram Eldar_, Nov 02 2019