A333139 The number of regions inside a decagon formed by the straight line segments mutually connecting all vertices and all points that divide the sides into n equal parts.

220, 4220, 25220, 84280, 217800, 456640, 873090, 1501520, 2436020, 3736540, 5523970, 7830800, 10879460, 14665340, 19398660, 25173960, 32203320, 40502280, 50458120, 61995140, 75517160

Offset: 1

Author

Scott R. Shannon and N. J. A. Sloane, Mar 09 2020

Keywords

• nonn
• more

Comments

The terms are from numeric computation - no formula for a(n) is currently known.

Links

• Scott R. Shannon, Decagon regions for n = 1.
• Scott R. Shannon, Decagon regions for n = 2.
• Scott R. Shannon, Decagon regions for n = 3.
• Scott R. Shannon, Decagon regions with random distance-based coloring for n = 1.
• Scott R. Shannon, Decagon regions with random distance-based coloring for n = 2.
• Scott R. Shannon, Decagon regions with random distance-based coloring for n = 3.
• Wikipedia, Decagon.

Crossrefs

Cf. A332417 (n-gons), A332418 (vertices), A332419 (edges), A007678, A092867, A331452, A331929.

Extensions

a(6)-a(21) from Lars Blomberg, May 18 2020