OFFSET
1,1
COMMENTS
This was originally based on the data in Jinyuan Wang's A324042, and then extended by Lars Blomberg.
Since the cells are either triangles or quadrilaterals, this is the sum of the two arrays A333286 and A333287.
It would be nice to have a formula for these entries. It is easy to see that the first column is 4n for n>=1.
LINKS
Lars Blomberg, Table of n, a(n) for n = 1..3240 (the first 80 rows)
Lars Blomberg, Scott R. Shannon and N. J. A. Sloane, Graphical Enumeration and Stained Glass Windows, 1: Rectangular Grids, (2021). Also arXiv:2009.07918.
EXAMPLE
Triangle begins:
4;
8, 8;
12, 22, 12;
16, 36, 36, 16;
20, 52, 70, 52, 20;
24, 66, 100, 100, 66, 24;
28, 82, 134, 160, 134, 82, 28;
...
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
N. J. A. Sloane, Mar 20 2020
EXTENSIONS
a(29) and beyond from Lars Blomberg, Apr 23 2020
STATUS
approved