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 A015766 #20 Jan 08 2025 12:46:31 %S A015766 1,2,3,6,19689,39378 %N A015766 Numbers k such that phi(k) | sigma_8(k). %C A015766 sigma_8(n) is the sum of the 8th powers of the divisors of n. %C A015766 sigma(16j+8,x)/phi(x) is an integer for j = 0, ..., 500 and 6 actual terms of this sequence. Compare to A015759, A015762, A015770 and A091285. - _Labos Elemer_, May 27 2004 %C A015766 No additional terms up to 5 million. - _Harvey P. Dale_, Jan 31 2016 %t A015766 Select[Range[40000],Divisible[DivisorSigma[8,#],EulerPhi[#]]&] (* _Harvey P. Dale_, Jan 31 2016 *) %Y A015766 Cf. A015759, A015762, A015770, A091285. %K A015766 nonn,more %O A015766 1,2 %A A015766 _Robert G. Wilson v_