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A062823
Numbers k such that the number of divisors of k divides the number of divisors of the totient of k.
1
1, 3, 7, 11, 13, 14, 15, 19, 22, 23, 25, 28, 29, 31, 35, 39, 41, 43, 44, 46, 47, 50, 53, 55, 56, 59, 61, 62, 67, 68, 70, 71, 73, 77, 78, 79, 82, 83, 86, 87, 88, 89, 91, 92, 93, 94, 95, 97, 99, 103, 107, 109, 110, 111, 112, 113, 115, 117, 118, 119, 122, 124, 127, 129, 131
OFFSET
0,2
LINKS
EXAMPLE
For n={3,11,29}, phi(n)={2,10,28}, d(phi(n))={2,4,6}, d(n)=2, quotient={1,2,3}.
MATHEMATICA
Select[Range@ 132, Mod @@ DivisorSigma[0, {EulerPhi@ #, #}] == 0 &] (* Michael De Vlieger, Jun 29 2018 *)
PROG
(PARI) select(m->frac(numdiv(eulerphi(m))/numdiv(m)) == 0, [1..500]) \\ Harry J. Smith, Aug 11 2009
CROSSREFS
Sequence in context: A055050 A096346 A104534 * A031466 A045062 A111068
KEYWORD
nonn
AUTHOR
Labos Elemer, Jul 20 2001
EXTENSIONS
Incorrect formula deleted by Jon E. Schoenfield, Jul 02 2018
STATUS
approved