A244020 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.

4, 6, 3, 3, 6, 16, 84, 1716, 719628

Offset: 1

Author

N. J. A. Sloane, Jun 20 2014

Keywords

• nonn
• more

Comments

A140468 is the main sequence for this problem. We have a(n) = b(n)-b(n-2), where b(n) = A140468(n).

Links

• Joshua Cooper, Mark Walters, Iterated point-line configurations grow doubly-exponentially, Discrete Comput. Geom. 43 (2010), no. 3, 554-562. MR2587837 (2011f:51016) 51M04 (52C35).
• Shalosh B. Ekhad, Doron Zeilberger, Enumerative Geometrical Genealogy (Or: The Sex Life of Points and Lines), arXiv:1406.5157 [math.CO], (19-June-2014)

Crossrefs

Related sequences: A140468, A244020-A244026.