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A175952 The generations in which the transformation described in A072207 does not lead to a doubling of the cardinality of the set of rationals. 1

%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(s-1)}. [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

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Last modified June 21 12:48 EDT 2021. Contains 345364 sequences. (Running on oeis4.)