A067156 Number of regions in regular n-gon which are 9-gons.

1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 35, 0, 0, 0, 0, 0, 123, 0, 0, 88, 45, 0, 0, 0, 0, 0, 51, 0, 0, 0, 165, 0, 114, 0, 118, 120, 61, 124, 0, 192, 195, 66, 67, 272, 138, 0, 568, 360, 146, 222, 600, 0, 231, 156, 237, 800, 567, 410, 664, 84, 255, 344, 174

Offset: 9

Author

Sascha Kurz, Jan 06 2002

Keywords

• nonn

Examples

			a(9)=1 because drawing the regular 9-gon with all its diagonals yields 1 9-gon.
		

References

• B. Poonen and M. Rubinstein, Number of Intersection Points Made by the Diagonals of a Regular Polygon, SIAM J. Discrete Mathematics, Vol. 11, pp. 135-156.

Links

• Scott R. Shannon, Table of n, a(n) for n = 9..765
• Sascha Kurz, m-gons in regular n-gons
• B. Poonen and M. Rubinstein, The number of intersection points made by the diagonals of a regular polygon, SIAM J. on Discrete Mathematics, Vol. 11, No. 1, 135-156 (1998).
• Sequences formed by drawing all diagonals in regular polygon

Crossrefs

Cf. A007678, A067168, A064869, A067151, A067152, A067153, A067154, A067155, A067157, A067158, A067159.

Extensions

a(86) and beyond by Scott R. Shannon, Dec 04 2021