OFFSET
1,2
COMMENTS
The condition that the columns be in nonincreasing order is equivalent to considering nonequivalent matrices up to permutation of columns.
FORMULA
a(n) = Sum_{d|n} A331571(n/d, d).
EXAMPLE
The a(4) = 11 matrices are:
[1 0 0 0] [1 1] [1 0] [1 0] [1 1 0 0] [1 0 0 0]
[0 1 0 0] [1 0] [1 1] [0 1] [0 0 1 0] [0 1 1 0]
[0 0 1 0] [0 1] [0 1] [1 1] [0 0 0 1] [0 0 0 1]
[0 0 0 1]
.
[1 0 0 0] [1 1 1 0] [1 1 0 0] [1 0 0 0] [1 1 1 1]
[0 1 0 0] [0 0 0 1] [0 0 1 1] [0 1 1 1]
[0 0 1 1]
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Jan 24 2020
STATUS
approved