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 A353685 #6 May 06 2022 15:26:22 %S A353685 1,3,5,7,11,13,15,17,19,23,26,27,29,31,33,35,37,38,39,41,43,45,47,49, %T A353685 51,53,55,57,58,59,61,65,67,69,71,73,74,77,79,82,83,85,86,87,89,91,95, %U A353685 97,99,101,103,104,107,109,111,113,115,116,117,118,119,121,122,123,125,127,129,131,133,134,135,137,139,141,143 %N A353685 Numbers k for which phi(sigma(k)) <= phi(k). %C A353685 Numbers k such that A062401(k) <= A000010(k). %H A353685 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a> %t A353685 Select[Range[150], EulerPhi[DivisorSigma[1, #]] <= EulerPhi[#] &] (* _Amiram Eldar_, May 06 2022 *) %o A353685 (PARI) isA353685(n) = (eulerphi(sigma(n))<=eulerphi(n)); %Y A353685 Cf. A000010, A000203, A062401, A353683 (complement). %Y A353685 Positions of zeros in A353681. Positions of terms <= 0 in A353636. %Y A353685 Disjoint union of A006872 and A353686. %K A353685 nonn %O A353685 1,2 %A A353685 _Antti Karttunen_, May 06 2022