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 A181344 #10 Feb 23 2020 14:58:39
%S A181344 0,0,1,1,5,25,161,1112,8787,76156,728699,7609065,86162795,1050755884,
%T A181344 13728407061,191309852944
%N A181344 Number of n X n matrices over {0,1} with rows and columns summing to 3, rows and columns sorted (>=) by value.
%H A181344 Bert Dobbelaere, <a href="/A181344/a181344.pdf">Illustration of initial terms</a>
%e A181344 n=4: {1110,1101,1011,0111} is the only matrix where each row (column) - read as a binary number - is equal to or larger than the previous one, so a(4)=1.
%Y A181344 Cf. A000512, A001501, A181345.
%K A181344 hard,more,nonn
%O A181344 1,5
%A A181344 Michael Steyer (m.steyer(AT)osram.de), Oct 14 2010
%E A181344 a(10)-a(16) from _Bert Dobbelaere_, Feb 23 2020