%I
%S 6,12,15,18,20,21,24
%N The generations in which the transformation described in A072207 does not lead to a doubling of the cardinality of the set of rationals.
%F By definition, this is {s: A072207(s) < 2*A072207(s1)}. [R. J. Mathar, Oct 30 2010]
%e The set size in A072207 doubles with the first 5 transformations, 1>2>4>8>16>32. a(1)=6 because the 6th application grows the set only 32>52 (to less than 64).
%Y Cf. A072207.
%K more,nonn
%O 1,1
%A _Dylan Hamilton_, Oct 28 2010
%E Rewrote definition in terms of A072207.  _R. J. Mathar_ Oct 30 2010
%E Edited by _N. J. A. Sloane_, Nov 24 2016
