

A175424


a(n) = number of steps of iterations of {(((D_k^D_(k1))^D_(k2))^...)^D_1, where D_k = kth digit D of number r and k = the number digit of number r in decimal expansion of r (A055642)} needed to reach a singledigit number starting at r = n, or a(n) = 1 if a singledigit number is never reached.


7



0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 3, 3, 2, 1, 1, 1, 4, 3, 1, 1, 3, 3, 3, 1, 1, 2, 2, 3, 3, 3, 2, 2, 2, 1, 1, 2, 3, 2, 4, 3, 2, 3, 2, 1, 1, 3, 3, 2, 3, 3, 3, 3, 2, 1, 1, 4, 3, 3, 3, 3, 3, 2, 3, 1, 1, 3, 2, 3, 2, 3, 2, 2, 2, 1, 1, 3, 3, 3, 3, 2, 2, 2, 2
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,25


COMMENTS

Conjecture: max(a(n)) = 4.


LINKS

Table of n, a(n) for n=0..99.


EXAMPLE

For n = 33: a(33) = 4 because for the number 33 there are 4 steps of defined iteration: {3^3 = 27}, {7^2 = 49}, {9^4 = 6561}, {((1^6)^5)^6 = 1}.


CROSSREFS

Cf. A175419, A175420, A175421, A175422, A175423, A175425, A175426, A175427.
Sequence in context: A100640 A242779 A215065 * A144401 A034929 A099509
Adjacent sequences: A175421 A175422 A175423 * A175425 A175426 A175427


KEYWORD

sign,base


AUTHOR

Jaroslav Krizek, May 09 2010


STATUS

approved



