OFFSET
1,2
COMMENTS
Equivalently, the number of cycles on an (n+1) X (n+1) grid that touch each of the four outside edges.
LINKS
Andrey Zabolotskiy, Table of n, a(n) for n = 1..16
Anthony J. Guttmann and Iwan Jensen, Effect of Confinement: Polygons in Strips, Slabs and Rectangles, in: Polygons, Polyominoes and Polycubes, LNP 775, Springer, 2009. See Table 10.2 on p. 239.
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Oct 04 2017
STATUS
approved