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 A260340 #14 Apr 18 2020 17:15:14 %S A260340 1,1,1,1,1,1,1,1,1,1,1,1,6,1,1,1,1,22,22,1,1,1,1,130,550,130,1,1,1,1, %T A260340 822,16700,16700,822,1,1,1,1,6202,703297,3330915,703297,6202,1,1,1,1, %U A260340 52552,38135272,957659906,957659906,38135272,52552,1,1 %N A260340 Triangle read by rows: T(n,k) = number of sets of linear n-ads in k variables. %C A260340 T(n,k) is the number of nonequivalent n X n binary matrices with k ones in every row and column up to permutation of rows. - _Andrew Howroyd_, Apr 18 2020 %H A260340 Andrew Howroyd, <a href="/A260340/b260340.txt">Table of n, a(n) for n = 0..230</a> (rows 0..20) %H A260340 P. A. MacMahon, <a href="http://plms.oxfordjournals.org/content/s2-17/1/25.extract">Combinations derived from m identical sets of n different letters and their connexion with general magic squares</a>, Proc. London Math. Soc., 17 (1917), 25-41. %F A260340 T(n,k) = T(n,n-k). - _Andrew Howroyd_, Apr 18 2020 %e A260340 Triangle begins: %e A260340 1; %e A260340 1, 1; %e A260340 1, 1, 1; %e A260340 1, 1, 1, 1; %e A260340 1, 1, 6, 1, 1; %e A260340 1, 1, 22, 22, 1, 1; %e A260340 1, 1, 130, 550, 130, 1, 1; %e A260340 1, 1, 822, 16700, 16700, 822, 1, 1; %e A260340 1, 1, 6202, 703297, 3330915, 703297, 6202, 1, 1; %e A260340 ... %Y A260340 Columns k=0..4 are A000012, A000012, A002137, A333899, A333900. %Y A260340 Row sums are A333891. %Y A260340 Cf. A008300, A133687, A257463. %K A260340 nonn,tabl %O A260340 0,13 %A A260340 _N. J. A. Sloane_, Jul 30 2015 %E A260340 Extended to include k=0 and more terms added by _Andrew Howroyd_, Apr 18 2020