OFFSET
1,3
COMMENTS
Percolation theory focuses on patterns that provide connectivity. Polyominoes that connect all boundaries of a square are in the percolation neighborhood. This subclass of symmetric polyominoes distinguishes itself for its beauty and its unusual enumeration pattern.
LINKS
Craig Knecht, Change of state - math becomes art
Craig Knecht, Polyominoe enumeration
Wikipedia, Connective polyominoes with 4 sym-axis
Wikipedia, Water Retention on Mathematical Surfaces
FORMULA
a(2*n) = a(2*n-1) = A268758(n). - Andrew Howroyd, May 03 2020
EXAMPLE
The ones in this example provide the connective pattern that joins all boundaries of the square.
0 1 1 1 0
1 0 1 0 1
1 1 1 1 1
1 0 1 0 1
0 1 1 1 0
CROSSREFS
KEYWORD
nonn
AUTHOR
Craig Knecht, Feb 02 2016
EXTENSIONS
Terms a(17) and beyond from Andrew Howroyd, May 03 2020
STATUS
approved