A331710 - OEIS

%I #7 Jan 25 2020 20:55:32

%S 1,3,45,1987,190379,30474159,7287577611,2436916655479,

%T 1085776582252197,621663581843731535,444746638465623906738,

%U 388773810523972862494769,407727415097448880517583006,505268334502886263575349570013,730406898110019766652845079212010

%N Number of nonnegative integer matrices with n columns and any number of distinct nonzero rows with column sums 3 and columns in nonincreasing lexicographic order.

%C The condition that the columns be in nonincreasing order is equivalent to considering nonequivalent matrices up to permutation of columns.

%H Andrew Howroyd, <a href="/A331710/b331710.txt">Table of n, a(n) for n = 0..100</a>

%F a(n) = (1/n!)*Sum_{k=0..n} abs(Stirling1(n, k)) * A331645(k).

%e The a(1) = 3 matrices are:

%e   [2]  [1]  [3]

%e   [1]  [2]

%Y Row n=3 of A331572.

%Y Cf. A331645, A331709.

%K nonn

%O 0,2

%A _Andrew Howroyd_, Jan 25 2020