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A333103
Quasiperfect cototient numbers: numbers k such that the sum of the iterated cototient function of k is equal to k+1.
1
6, 14, 62, 254, 16382, 78585, 87465, 262142, 1048574
OFFSET
1,1
COMMENTS
If m is in A050475 then 2^m - 2 is a term.
3*10^8 < a(10) <= 4294967292.
EXAMPLE
6 is a term since A051953(6) = 4, A051953(4) = 2, A051953(2) = 1, and 4 + 2 + 1 = 7 = 6 + 1.
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