OFFSET
1,3
LINKS
Jeff Bowermaster, Illustration of a(1)..a(4)
Jeff Bowermaster, Illustration of a(5)
Code Golf Stack Exchange, Number of distinct tilings of an n X n square with free n-polyominoes
CROSSREFS
KEYWORD
nonn,hard,more,nice
AUTHOR
Jeff Bowermaster, Oct 01 2019
EXTENSIONS
a(7) from Peter Kagey, Oct 10 2019, based on the Stack Exchange link.
a(8) from Christian Sievers, Oct 13 2019, based on the Stack Exchange link.
STATUS
approved