OFFSET
0,2
COMMENTS
The condition that the columns be in nonincreasing order is equivalent to considering nonequivalent matrices up to permutation of columns.
EXAMPLE
The a(2) = 2 matrices are:
[1 1] [1 0] [1 0] [2 1] [2 0] [1 0] [2 2]
[1 0] [1 1] [0 1] [0 1] [0 2] [1 2]
[0 1] [0 1] [1 1]
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Jan 25 2020
STATUS
approved