OFFSET
1,1
COMMENTS
If m is in A050475 then 2^m - 2 is a term.
3*10^8 < a(10) <= 4294967292.
LINKS
EXAMPLE
MATHEMATICA
cot[n_] := n - EulerPhi[n]; s[n_] := Plus @@ FixedPointList[cot, n]; Select[Range[10^5], s[#] == 2*# + 1 &]
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Mar 07 2020
STATUS
approved