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A133144
Start with n and repeatedly apply the powerback map of A133048. Sequence gives number of steps to the point where the next number would be one that has appeared before.
2
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, 0, 4, 6, 3, 2, 1, 1, 1, 7, 3, 2, 3, 6, 3, 7, 1, 1, 2, 2, 4, 3, 3, 3, 2, 5, 1, 1, 2, 5, 2, 2, 6, 5, 4, 2, 1, 1, 3, 7, 2, 4, 4, 5, 4, 5, 1, 1, 4, 4, 5, 2, 3, 6, 4, 3, 1, 1, 4, 5, 3, 5, 5, 3, 4, 5, 1, 1, 3, 9, 4, 6, 2, 2, 5, 3
OFFSET
0,25
COMMENTS
It is conjectured that every number eventually reaches a fixed point (see A131571) or the cycle of length 2 given by (175 <-> 78125).
EXAMPLE
n, a(n), trajectory
22, 1, [22, 4]
23, 1, [23, 9]
24, 2, [24, 16, 6]
25, 0, [25]
26, 4, [26, 36, 216, 12, 2]
27, 6, [27, 49, 6561, 15625, 194400, 2304, 9]
28, 3, [28, 64, 4096, 0]
29, 2, [29, 81, 1]
30, 1, [30, 3]
31, 1, [31, 1]
32, 1, [32, 8]
33, 7, [33, 27, 49, 6561, 15625, 194400, 2304, 9]
34, 3, [34, 64, 4096, 0]
35, 2, [35, 125, 25]
36, 3, [36, 216, 12, 2]
37, 6, [37, 343, 243, 162, 64, 4096, 0]
38, 3, [38, 512, 10, 1]
39, 7, [39, 729, 567, 588245, 5242880000, 8589934592, 105911076180375000000000, 0]
CROSSREFS
Sequence in context: A319931 A192133 A244109 * A342384 A192134 A322402
KEYWORD
nonn,base
AUTHOR
J. H. Conway and N. J. A. Sloane, Jan 01 2008
STATUS
approved