OFFSET
1,1
COMMENTS
Most terms m of the sequence have k = omega(m) = 1, only 132 and 16371 with k=3 are found. Further searches did not find any more terms with k >= 3. k has to be odd in any case, this can be easily seen by looking at the parity of the prime factors. Perhaps someone with a stronger computer can find more numbers with k>1, if there are any. [There are no other terms that are not prime powers among the first 1000 terms. - Amiram Eldar, Sep 25 2021]
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..1000
EXAMPLE
16371 = 3^2 * 17 * 107 = 3^2 + 17^3 + 107^2.
MATHEMATICA
f[p_, e_] := p^PrimitiveRoot[p]; q[n_] := Plus @@ f @@@ FactorInteger[n] == n; Select[Range[2, 10^5], q] (* Amiram Eldar, Sep 25 2021 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Sven Simon, Nov 28 2004
EXTENSIONS
Shorter name from Amiram Eldar, Sep 25 2021
STATUS
approved