A091294 Numbers n such that phi(n) = phi(3n+1).

75973, 301513, 2053393, 3404053, 4022573, 5399123, 6461473, 8395613, 9848813, 11804173, 14124133, 15680573, 17173333, 20705533, 23609083, 28988353, 30290563, 32845633, 35025943, 36791813, 39630803, 42598663, 43605943, 44116333, 53795083, 54396533, 54563693

Offset

1,1

Comments

Is it accidental that most terms have form 10k+3?

Links

Donovan Johnson, Table of n, a(n) for n = 1..100

Mathematica

Do[If[Equal[EulerPhi[n], EulerPhi[3*n+1]], Print[n]], {n, 1, 100000000}]

Prog

(PARI) is(n)=my(t=eulerphi(3*n+1)); t<n && t==eulerphi(n) \\ Charles R Greathouse IV, May 19 2013

Crossrefs

Cf. A000010, A092272.

Sequence in context: A243959 A236807 A251470 * A096518 A234895 A096888

Adjacent sequences: A091291 A091292 A091293 * A091295 A091296 A091297

Keyword

nonn

Author

Labos Elemer, Feb 19 2004

Extensions

a(20)-a(27) from Donovan Johnson, Jul 27 2011

Status

approved