A352144 The number of interior points that are intersections of exactly two chords for a 2n-gon where all its vertices are joined by lines (cf. A006561).

0, 1, 12, 40, 140, 228, 644, 1168, 1512, 3360, 5280, 6144, 11284, 15680, 13800, 28448, 37264, 42444, 60648, 75720, 75012, 114400, 138644, 152064, 198200, 234208, 254988, 321048, 372708, 375060, 494140, 564800, 605352, 728960, 823480, 894816, 1039404, 1161888, 1241760, 1439440, 1595720

Offset: 1

Author

Scott R. Shannon and N. J. A. Sloane, Mar 06 2022

Keywords

• nonn

Comments

For the (2n+1)-gon the number of interior simple intersections is given by binomial(n,4) as all interior points are simple. For the 2n-gon, this sequence, no such formula is currently known.

See A335102 for images of the 2n-gons.

Links

• Scott R. Shannon, Table of n, a(n) for n = 1..72

Crossrefs

Cf. A292104 (all n-gons), A006561, A335102.