A064804 Numbers 2*k such that phi(2*k + 2) < phi(2*k).

16, 22, 28, 34, 38, 40, 46, 52, 58, 64, 68, 76, 82, 86, 88, 94, 98, 100, 106, 112, 118, 124, 128, 130, 134, 136, 142, 148, 152, 154, 158, 160, 166, 172, 178, 184, 188, 190, 194, 196, 202, 206, 208, 214, 218, 220, 226, 232, 236, 238, 244, 248, 250, 256, 262, 268

Offset: 1

Author

Robert G. Wilson v, Oct 21 2001

Keywords

• easy
• nonn

Links

• Harry J. Smith, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A001837.

Programs

Mathematica

2Select[ Range[200], EulerPhi[2# + 2] < EulerPhi[2# ] & ]

PARI

{ n=e=0; forstep (m=2, 10^9, 2, f=eulerphi(m); if (fHarry J. Smith, Sep 26 2009

Extensions

a(41)-a(56) from Harry J. Smith, Sep 26 2009

Name clarified by Sean A. Irvine, Jul 28 2023