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 A331636 #11 Oct 15 2024 18:06:50
%S A331636 1,5,17,109,557,5785,47357,596365,7151841,106763725,1622633597,
%T A331636 28757539337,526858352477,10758375762109,230342261913169,
%U A331636 5344946955452877,130370767029201437,3394996816992588345,92801587319328673277,2681375183085608280093
%N A331636 Number of nonnegative integer matrices with nonzero rows, total sum n and columns with equal sums.
%H A331636 Andrew Howroyd, <a href="/A331636/b331636.txt">Table of n, a(n) for n = 1..200</a>
%F A331636 a(n) = Sum_{d|n} A316674(n/d, d).
%e A331636 The a(2) = 5 matrices are:
%e A331636 [1] [1 0] [0 1] [2] [1 1]
%e A331636 [1] [0 1] [1 0]
%Y A331636 Cf. A316674.
%K A331636 nonn
%O A331636 1,2
%A A331636 _Andrew Howroyd_, Jan 23 2020