OFFSET
1,3
COMMENTS
Apparently, the least number that reaches 1 after k iterations is A082449(k-1) (checked numerically for 1 <= k <= 17).
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Daeyeoul Kim, Umit Sarp, and Sebahattin Ikikardes, Iterating the Sum of Möbius Divisor Function and Euler Totient Function, Mathematics, Vol. 7, No. 11 (2019), pp. 1083-1094.
MATHEMATICA
f[p_, e_] := p - 1; u[1] = 1; u[n_] := Times @@ (f @@@ FactorInteger[n]); a[n_] := Length @ FixedPointList[u, n] - 2; Array[a, 100]
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Apr 08 2020
STATUS
approved