OFFSET
1,3
EXAMPLE
a(7)= 4 because 7 -> phi(7)= 6 -> 3 -> phi(3)= 2 -> 1, hence the trajectory {7 -> 6 -> 3 -> 2 -> 1} with 4 iterations.
MATHEMATICA
f[n_]:=Module[{a=n, k=0}, While[a!=1, k++; If[EvenQ[a], a=a/2, a=EulerPhi[a]]]; k]; Table[f[n], {n, 1, 150}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Michel Lagneau, Jul 07 2015
STATUS
approved