OFFSET
1,2
COMMENTS
Also, unitary harmonic numbers k whose harmonic mean of the unitary divisors of k is a unitary divisor of k.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..84
EXAMPLE
6 is a term since the arithmetic mean of its unitary divisors, {1, 2, 3, 6}, is 3, and 3 is also a unitary divisor of 6.
MATHEMATICA
q[n_] := Module[{f = FactorInteger[n], d, s, m}, d = 2^Length[f]; s = Times @@ (1 + Power @@@ f); m = s/d; IntegerQ[m] && Divisible[n, m] && CoprimeQ[m, n/m]]; Select[Range[10^6], q]
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Apr 19 2022
STATUS
approved