Stack polyomino

A stack is a polyomino a diamond that is diagonally directed from two adjacent corners. When convex, it can be thought of as being composed of sets of "bands", each smaller than the previous, being stacked on top of each other, hence the name. A stack is a subclass of bar chart.

Symbol

Dir42c\textrm{Dir}_{4}^{2\textrm{c}}

Regex

ru(ru)*(lu)*ld

Polyomino list

ru2luld
4
5
6
7
8
ru3luld
7
8