OFFSET
1,2
COMMENTS
The condition that the rows be in nonincreasing order is equivalent to considering nonequivalent matrices up to permutation of rows.
FORMULA
a(n) = Sum_{d|n} A331161(n/d, d).
EXAMPLE
The a(4) = 13 matrices are:
[1 0 0 0] [1 0] [1] [1 1] [2 0] [1 0] [2]
[0 1 0 0] [1 0] [1] [1 0] [0 1] [1 0] [1]
[0 0 1 0] [0 1] [1] [0 1] [0 1] [0 2] [1]
[0 0 0 1] [0 1] [1]
.
[2 1] [2 0] [1 2] [3] [2] [4]
[0 1] [0 2] [1 0] [1] [2]
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Jan 11 2020
STATUS
approved