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%I #13 Jun 20 2014 13:32:50
%S 4,6,3,3,6,16,84,1716,719628
%N Number of new points at the n-th step of the following iteration, starting with four points in general position in the real projective plane: dualize the current pointset to a family of lines, take all intersections of those lines, repeat.
%C A140468 is the main sequence for this problem. We have a(n) = b(n)-b(n-2), where b(n) = A140468(n).
%H Joshua Cooper, Mark Walters, <a href="http://arxiv.org/abs/0807.1549">Iterated point-line configurations grow doubly-exponentially</a>, Discrete Comput. Geom. 43 (2010), no. 3, 554-562. MR2587837 (2011f:51016) 51M04 (52C35).
%H Shalosh B. Ekhad, Doron Zeilberger, <a href="http://arxiv.org/abs/1406.5157">Enumerative Geometrical Genealogy (Or: The Sex Life of Points and Lines)</a>, arXiv:1406.5157 [math.CO], (19-June-2014)
%Y Related sequences: A140468, A244020-A244026.
%K nonn,more
%O 1,1
%A _N. J. A. Sloane_, Jun 20 2014
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