|
Search: id:A049108
|
|
|
| A049108 |
|
Number of iterations of Euler phi function needed to reach 1 starting at n (n is counted). |
|
+0
14
|
|
| 1, 2, 3, 3, 4, 3, 4, 4, 4, 4, 5, 4, 5, 4, 5, 5, 6, 4, 5, 5, 5, 5, 6, 5, 6, 5, 5, 5, 6, 5, 6, 6, 6, 6, 6, 5, 6, 5, 6, 6, 7, 5, 6, 6, 6, 6, 7, 6, 6, 6, 7, 6, 7, 5, 7, 6, 6, 6, 7, 6, 7, 6, 6, 7, 7, 6, 7, 7, 7, 6, 7, 6, 7, 6, 7, 6, 7, 6, 7, 7, 6, 7, 8, 6, 8, 6, 7, 7, 8, 6, 7, 7, 7, 7, 7, 7, 8, 6, 7, 7, 8, 7, 8, 7, 7
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
FORMULA
|
By the definition of a(n) we have for n >= 2 the recursion a(n) = a(Phi(n)) + 1. - Ahmed Fares (ahmedfares(AT)my-deja.com), Apr 20 2001
|
|
EXAMPLE
|
If n=164 the trajectory is {164,80,32,16,8,4,2,1}. Its length is 8, thus a(164)=8.
|
|
MATHEMATICA
|
f[n_] := Length[ NestWhileList[ EulerPhi, n, Unequal, 2]] - 1; Table[ f[n], {n, 1, 105}]
|
|
CROSSREFS
|
Cf. A000010, A007755. Equals A003434 + 1.
Sequence in context: A096344 A030349 A085887 this_sequence A086925 A088858 A113312
Adjacent sequences: A049105 A049106 A049107 this_sequence A049109 A049110 A049111
|
|
KEYWORD
|
nonn,nice,easy
|
|
AUTHOR
|
Labos E. (labos(AT)ana.sote.hu)
|
|
|
Search completed in 0.002 seconds
|
