A196200 Numbers k such that Euler phi(Dedekind psi(k)) > k.

39270, 53130, 71610, 78540, 82110, 106260, 108570, 117810, 122430, 143220, 157080, 159390, 164010, 164220, 212520, 214830, 217140, 235620, 244860, 246330, 247170, 286440, 293370, 314160, 318780, 325710, 328020, 328440, 353430, 367290, 425040, 429660, 434280

Offset

1,1

Comments

Counterexamples to a conjecture by Sandor.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..66 from Indranil Ghosh)

Jozsef Sandor, On the Composition of Some Arithmetic Functions, II, Journal of Inequalities in Pure and Applied Mathematics (JIPAM), Volume 6, Issue 3, Article 73, 2005.

Mathematica

Select[Range[39270, 434280], EulerPhi[# * Sum[MoebiusMu[d]^2 / d, {d, Divisors[#]}]] > # &] (* Indranil Ghosh, Mar 11 2017 *)

Prog

(PARI) a(m) = {for (n=1, m, if (eulerphi(n * sumdiv( n, d, moebius(d)^2 / d)) > n, print1(n, ", ")); ); }

Crossrefs

Cf. A000010, A001615.

Sequence in context: A233955 A250515 A031667 * A378627 A274128 A144306

Adjacent sequences: A196197 A196198 A196199 * A196201 A196202 A196203

Keyword

nonn

Author

Michel Marcus, Dec 21 2012

Status

approved