OFFSET
1,2
COMMENTS
Sândor proved that lim sup psi(phi(n))/n = oo, hence this sequence is infinite.
REFERENCES
Jôzsef Sândor, On Dedekind’s arithmetical function, Seminarul de Teoria Structurilor, Univ. Timisoara, No. 51, 1988, pp. 1-15.
LINKS
Jôzsef Sândor, On the composition of some arithmetic functions, II, Journal of Inequalities in Pure and Applied Mathematics, Vol. 6, Issue 3, Article 73 (2005).
MATHEMATICA
psi[n_] := If[n < 1, 0, n*Sum[MoebiusMu[d]^2/d, {d, Divisors@n}]]; a={}; rm=0; Do[r=psi[EulerPhi[n]]/n; If[r>rm, rm=r; AppendTo[a, n]], {n, 1, 100000}]; a
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Oct 15 2017
STATUS
approved