A293711 Numbers k such that phi(sigma(k))/k < phi(sigma(m))/m for all m < k, where sigma is the sum of divisors function (A000203) and phi is Euler's totient function (A000010).

1, 3, 5, 11, 17, 23, 29, 59, 89, 149, 179, 239, 269, 359, 377, 389, 419, 839, 1049, 1259, 1889, 2099, 2309, 9239, 11549, 13859, 20789, 23099, 25409, 30029, 90089, 180179, 210209, 270269, 300299, 330329, 390389, 420419, 540539, 570569, 1017917, 1018013, 1021019

Offset

1,2

Links

Amiram Eldar, Table of n, a(n) for n = 1..127

Mathematica

a={}; rm=2; Do[r=EulerPhi[DivisorSigma[1, n]]/n; If[r<rm, rm=r; AppendTo[a, n]], {n, 1, 100000}]; a

Crossrefs

Cf. A000010, A000203, A062401.

Sequence in context: A244029 A106902 A343048 * A155938 A158318 A099596

Adjacent sequences: A293708 A293709 A293710 * A293712 A293713 A293714

Keyword

nonn

Author

Amiram Eldar, Oct 15 2017

Status

approved