

A063469


Numbers n such that tau(n)*3 = phi(n).


9




OFFSET

1,1


COMMENTS

"phi(n)=k*Tau[n] has at most finitely many solutions for any constant k or even for slowly increasing functions like k(n)=n^(epsilon)."  Labos Elemer, Jul 20 2001


LINKS

Table of n, a(n) for n=1..10.


MATHEMATICA

Select[Range[300], 3DivisorSigma[0, #]==EulerPhi[#]&] (* Harvey P. Dale, Sep 15 2016 *)


PROG

(PARI) for(n=1, 10^7, if(3*numdiv(n)==eulerphi(n), print(n)))


CROSSREFS

Cf. A062516.
Cf. A112954, A020488, A063470.
Sequence in context: A097182 A058525 A219036 * A155131 A160890 A319527
Adjacent sequences: A063466 A063467 A063468 * A063470 A063471 A063472


KEYWORD

fini,full,nonn


AUTHOR

Jason Earls, Jul 26 2001


EXTENSIONS

"full" keyword from Max Alekseyev, Mar 01 2010


STATUS

approved



