This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A331713 #8 Sep 11 2024 23:00:14
%S A331713 1,3,7,18,21,147,77,1119,2270,12273,1089,464200,4229,4148223,32941976,
%T A331713 159812905,66153,10211281004,263321,205923976532,2439257062679,
%U A331713 3086915165084,4199061,1526043270802300,311419986358517,4817701809545446,621665561741298232,1898993198795136209
%N A331713 Number of nonnegative integer matrices with pairwise distinct nonzero rows, the total sum of elements equal n, the same sum of elements in each column, and the columns coming in nonincreasing lexicographic order.
%C A331713 The condition that the columns be in nonincreasing order is equivalent to considering nonequivalent matrices up to permutation of columns.
%F A331713 a(n) = Sum_{d|n} A331572(n/d, d).
%e A331713 The a(2) = 3 matrices are:
%e A331713 [1 0] [1 1] [2]
%e A331713 [0 1]
%Y A331713 Cf. A331572.
%K A331713 nonn
%O A331713 1,2
%A A331713 _Andrew Howroyd_, Jan 25 2020