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A196200 Numbers k such that Euler phi(Dedekind psi(k)) > k. 1
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 (list; graph; refs; listen; history; text; internal format)
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
Sequence in context: A233955 A250515 A031667 * A274128 A144306 A234033
KEYWORD
nonn
AUTHOR
Michel Marcus, Dec 21 2012
STATUS
approved

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Last modified May 19 19:45 EDT 2024. Contains 372703 sequences. (Running on oeis4.)