A320946 a(n) is the number of left-perimeter tiles among all rhombic tilings of the 2n-gon.

1, 2, 9, 80, 1340

Offset

2,2

Comments

Also the number of right-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.

Formula

a(n) = (n-1) * A320945(n).

Example

a(4) = 9 because among the eight rhombic tilings of the octagon, 9 left-perimeter rhombi appear.

Crossrefs

Cf. A320944, A320945, A006245.

Sequence in context: A109519 A193208 A279055 * A135868 A212271 A147302

Adjacent sequences: A320943 A320944 A320945 * A320947 A320948 A320949

Keyword

nonn,more

Author

Bridget Tenner, Oct 24 2018

Status

approved