A320945 a(n) is the number of top-perimeter tiles among all rhombic tilings of the 2n-gon.

1, 1, 3, 20, 268

Offset

2,3

Comments

Also the number of bottom-perimeter tiles among all rhombic tilings of the 2n-gon. Tiles and polygons all have sides of length 1, as in A006245.

Links

Table of n, a(n) for n=2..6.

B. E. Tenner, Tiling-based models of perimeter and area, arXiv:1811.00082 [math.CO], 2018.

Example

a(4) = 3 because among the eight rhombic tilings of the octagon, 3 top-perimeter rhombi appear.

Crossrefs

Cf. A320944, A320946, A006245.

Sequence in context: A210906 A355215 A193194 * A166232 A136551 A266812

Adjacent sequences: A320942 A320943 A320944 * A320946 A320947 A320948

Keyword

nonn,more

Author

Bridget Tenner, Oct 24 2018

Status

approved