A098197 Smallest number m such that the trajectory of m under iteration of cototient function[=A051953] contains exactly n distinct numbers (including m and the fixed point=0). Or: the required number of iterations[=operations,transitions] is n-1.

0, 1, 2, 4, 6, 10, 18, 30, 42, 78, 114, 186, 294, 390, 582, 798, 1194, 1950, 2922, 4074, 5586, 7770, 11154, 15810, 22110, 30702, 42570, 53130, 68970, 105090, 159390, 206910, 278850, 361410, 462210, 688722, 1019202, 1389810, 2053770, 3011850

Offset

1,3

Comments

Analogous to A007755. Separating prime and composite least numbers is not more informative [contrary to totient-iterations] because trajectory-length=3 for all primes and except 2, all terms here are composite numbers.

Links

Table of n, a(n) for n=1..40.

Example

Trajectories for lengths=n=1,2,3,4 are: {0},{1,0},{2,1,0},{4,2,1,0}
n=15:{390,294,210,162,108,72,48,32,16,8,4,2,1,0}

Crossrefs

Cf. A051953, A000010, A007755, A098196.

Sequence in context: A340311 A025052 A142584 * A358443 A175941 A317536

Adjacent sequences: A098194 A098195 A098196 * A098198 A098199 A098200

Keyword

nonn

Author

Labos Elemer, Sep 16 2004

Status

approved