A259847 Number of steps to get from n to 1 by process of replacing with the Carmichael function lambda if the result is odd, or dividing by 2 if even.

0, 1, 2, 2, 3, 3, 4, 3, 4, 4, 5, 4, 5, 5, 3, 4, 5, 5, 6, 5, 4, 6, 7, 5, 6, 6, 6, 6, 7, 4, 5, 5, 5, 6, 5, 6, 7, 7, 5, 6, 7, 5, 6, 7, 5, 8, 9, 6, 6, 7, 5, 7, 8, 7, 6, 7, 6, 8, 9, 5, 6, 6, 4, 6, 5, 6, 7, 7, 7, 6, 7, 7, 8, 8, 6, 8, 5, 6, 7, 7, 8, 8, 9, 6, 5, 7, 7

Offset

1,3

Links

Table of n, a(n) for n=1..87.

Example

a(19)= 6 because 19 -> lambda(19)= 18 -> 9 -> lambda(9)= 6 -> 3 -> lambda(3)= 2 -> 1, hence the trajectory {19 -> 18 -> 9 -> 6 -> 3 -> 2 -> 1} with 6 iterations.

Mathematica

f[n_]:=Module[{a=n, k=0}, While[a!=1, k++; If[EvenQ[a], a=a/2, a=CarmichaelLambda[a]]]; k]; Table[f[n], {n, 1, 150}]

Crossrefs

Cf. A002322.

Sequence in context: A208280 A139141 A122953 * A259103 A334200 A128998

Adjacent sequences: A259844 A259845 A259846 * A259848 A259849 A259850

Keyword

nonn,easy

Author

Michel Lagneau, Jul 07 2015

Status

approved