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Start with n and repeatedly apply the powertrain map x -> A133500(x); a(n) is the fixed point that is eventually reached, or -1 if the trajectory never reaches a fixed point.
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%I #15 Jun 17 2017 01:11:02

%S 1,2,3,4,5,6,7,8,9,1,1,1,1,1,1,1,1,1,1,1,2,4,8,1,9,0,8,2,1,1,3,9,8,8,

%T 0,2,0,0,0,1,4,1,0,2,1,0,0,0,0,1,5,9,5,0,0,0,0,0,0,1,6,2,1,0,0,0,0,0,

%U 0,1,7,0,0,0,7,0,0,0,0,1,8,0,1,0,0,0,0,0,0,1,9,8,2,0,0,0,0,0,0,0,1

%N Start with n and repeatedly apply the powertrain map x -> A133500(x); a(n) is the fixed point that is eventually reached, or -1 if the trajectory never reaches a fixed point.

%C It is conjectured that a fixed point is always reached.

%C It is also conjectured that the only fixed points are the numbers 0 through 9, 2592, and 24547284284866560000000000 (see A135385).

%H Chai Wah Wu, <a href="/A287877/b287877.txt">Table of n, a(n) for n = 1..10000</a>

%Y Cf. A133500, A135385.

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Jun 16 2017