|
|
A333870
|
|
The number of iterations of the absolute Möbius divisor function (A173557) required to reach from n to 1.
|
|
2
|
|
|
0, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 2, 1, 2, 2, 3, 2, 3, 3, 4, 2, 2, 3, 2, 3, 4, 2, 3, 1, 3, 2, 3, 2, 3, 3, 3, 2, 3, 3, 4, 3, 2, 4, 5, 2, 3, 2, 2, 3, 4, 2, 3, 3, 3, 4, 5, 2, 3, 3, 3, 1, 3, 3, 4, 2, 4, 3, 4, 2, 3, 3, 2, 3, 3, 3, 4, 2, 2, 3, 4, 3, 2, 4, 4
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
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
|
|
|
EXAMPLE
|
a(3) = 2 since there are 2 iterations from 3 to 1: A173557(3) = 2 and A173557(2) = 1.
|
|
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
|
|
|
STATUS
|
approved
|
|
|
|