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 A015715 #25 Dec 27 2024 04:12:02 %S A015715 1,3,15,35,105,357,1045,1485,3135,3339,5049,10659,12441,16065,24871, %T A015715 24969,29029,33915,35343,39105,39585,50065,58435,64285,71145,74613, %U A015715 87087,87685,99693,124355,124605,132957,137885,140335,145145,150195 %N A015715 Odd integers m such that phi(m) | sigma(m). %C A015715 Subsequence of A236693. Proof: if n is in this sequence, then 2^phi(n) - 1 is divisible by n and 2^sigma(n) - 1 is divisible by 2^phi(n) - 1. Therefore, 2^sigma(n) == 1 (mod n) and n is in A236693. - _Jinyuan Wang_, Mar 13 2020 %H A015715 Amiram Eldar, <a href="/A015715/b015715.txt">Table of n, a(n) for n = 1..10000</a> (calculated using data from Jud McCranie; terms 1..1000 from Donovan Johnson) %t A015715 Select[Range[1,151001,2],Divisible[DivisorSigma[1,#],EulerPhi[#]]&] (* _Harvey P. Dale_, Sep 16 2016 *) %o A015715 (PARI) isok(m) = (m % 2) && !(sigma(m) % eulerphi(m)); \\ _Michel Marcus_, Mar 14 2020 %Y A015715 Subsequence of A020492 and A236693. %Y A015715 Cf. A000010, A000203. %K A015715 nonn %O A015715 1,2 %A A015715 _Robert G. Wilson v_ %E A015715 Offset corrected by _Donovan Johnson_, Jan 18 2012