OFFSET
0,2
COMMENTS
The condition that the columns be in decreasing order is equivalent to considering nonequivalent matrices with distinct columns up to permutation of columns.
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..100
FORMULA
a(n) = (1/n!)*Sum_{k=0..n} abs(Stirling1(n, k)) * A331645(k).
EXAMPLE
The a(1) = 3 matrices are:
[2] [1] [3]
[1] [2]
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Jan 25 2020
STATUS
approved