OFFSET
1,4
LINKS
George Sicherman, Catalogue of Blunt Polytans
EXAMPLE
There are 3 ditans. Only the square ditan lacks acute corners, so a(2)=1.
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
George Sicherman, Jun 05 2018
EXTENSIONS
a(15)-a(20) from John Mason, Jan 07 2022
STATUS
approved