OFFSET
1,1
REFERENCES
Branko Gruenbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Sections 2.7, 6.2 and 9.4.
CROSSREFS
KEYWORD
hard,nonn
AUTHOR
Joseph Myers, Oct 15 2011
EXTENSIONS
a(20)-a(26) from Aaron N. Siegel, Jun 03 2022
STATUS
approved