OFFSET
1,1
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..30
S. Butler and S. Osborne, Counting tilings by taking walks, 2012.
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Dec 27 2012
EXTENSIONS
a(8)-a(20) from Andrew Howroyd, Nov 15 2015
STATUS
approved