

A217754


Number of different kinds of polygonal regions with finite area in the exterior of a regular ngon with all diagonals drawn.


1



0, 0, 0, 0, 1, 1, 2, 2, 4, 3, 4, 4, 4, 4, 5
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OFFSET

3,7


LINKS

Table of n, a(n) for n=3..17.


EXAMPLE

a(7) = 1 since the 35 exterior regions of the regular heptagon built by all diagonals consist of one kind of polygon (with finite area), i. e. 1 triangle (7 times), and three different regions with infinite area (two 7 times, one 14 times).
a(8) = 1 since the 64 exterior regions of the regular octagon built by all diagonals consist of one kind of polygon (with finite area), i. e. 2 triangles (one 8 times, one 16 times), and three different regions with infinite area (one 8 times, two 16 times).
a(9) = 2 since the 117 exterior regions of the regular 9gon (nonagon) built by all diagonals consist of two different kinds of polygons (with finite area), i. e. 3 triangles (one 9 times, two 18 times) and 2 quadrilaterals (each 9 times), and four different regions with infinite area (two 9 times, two 18 times).


CROSSREFS

Cf. A187782, A217746, A217749, A217750, A217751, A217752, A217753.
Sequence in context: A283187 A324391 A087808 * A319397 A094950 A087874
Adjacent sequences: A217751 A217752 A217753 * A217755 A217756 A217757


KEYWORD

nonn


AUTHOR

Martin Renner, Mar 23 2013


STATUS

approved



