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 A331637 #9 Oct 15 2024 18:06:46
%S A331637 1,4,14,89,542,5156,47294,570074,7103343,104493608,1622632574,
%T A331637 28411638982,526858348382,10699857854372,230297862127828,
%U A331637 5330284144906443,130370767029135902,3390229775073259800,92801587319328411134,2679531116538955252338
%N A331637 Number of binary matrices with nonzero rows, a total of n ones and each column with the same number of ones.
%H A331637 Andrew Howroyd, <a href="/A331637/b331637.txt">Table of n, a(n) for n = 1..200</a>
%F A331637 a(n) = Sum_{d|n} A262809(n/d, d).
%e A331637 The a(2) = 4 matrices are:
%e A331637 [1] [1 0] [0 1] [1 1]
%e A331637 [1] [0 1] [1 0]
%Y A331637 Cf. A262809.
%K A331637 nonn
%O A331637 1,2
%A A331637 _Andrew Howroyd_, Jan 23 2020