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
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
KEYWORD
nonn,more
AUTHOR
Bridget Tenner, Oct 24 2018
STATUS
approved