%N Let k'' be the result of applying the powertrain map of A133500 twice to k. Sequence gives conjectured list of all possible values of k''.
%C Sequence is believed to be finite.
%C All terms are members of A002473. Members of A002473 not present here are given in A133185. However, no proof is known that the missing numbers from A002473 (14, 21, 24, 30, ...) really are missing.
%C To settle this, one would, for example, have to prove that no number of the form 2^i*3^j*5^k*7^l exists with powertrain value 14.
%C The entries are based on a search of all numbers k such that k' = powertrain(k) <= 10^120.
%H N. J. A. Sloane, <a href="/A133184/b133184.txt">Table of n, a(n) for n = 1..10001</a>
%A _J. H. Conway_ and _N. J. A. Sloane_, Jan 01 2008