OFFSET
1,1
COMMENTS
A polyglass is column convex if the intersection of its interior with any vertical line through the centers of the cells is connected.
LINKS
EXAMPLE
There are four triglasses that are not column convex. So a(2) = A319324(3) - 4 = 84.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
David Bevan, Sep 27 2018
STATUS
approved