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 A112587 #8 Feb 16 2025 08:32:59 %S A112587 1,2,3,4,5,6,8,9,10,12,14,15,16,18,20,24,28,30,36,40,42,48,60,72,84, %T A112587 90,120 %N A112587 Numbers m such that phi(m) <= 2*tau(m), where phi=A000010 and tau=A000005. %C A112587 Complement of A112588. %H A112587 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/TotientFunction.html">Totient Function</a> %H A112587 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DivisorFunction.html">Divisor Function</a> %t A112587 Select[Range[150],EulerPhi[#]<=2DivisorSigma[0,#]&] (* _Harvey P. Dale_, Mar 04 2013 *) %o A112587 (PARI) is(n)=eulerphi(n)<=2*numdiv(n) \\ _Charles R Greathouse IV_, Feb 21 2013 %Y A112587 Cf. A020488. %K A112587 nonn,fini,full %O A112587 1,2 %A A112587 _Reinhard Zumkeller_, Sep 14 2005