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 A321446 #32 Jan 24 2024 18:33:14 %S A321446 1,1,2,10,72,624,6522,80178,1129368,17917032,316108752,6138887616, %T A321446 130120838400,2989026225696,73964789192400,1961487062520720, %U A321446 55495429438186920,1668498596700706440,53122020640948010640,1785467619718933936560,63175132023953553400440 %N A321446 Number of (0,1)-matrices with n ones, no zero rows or columns, and distinct rows and columns. %H A321446 Andrew Howroyd, <a href="/A321446/b321446.txt">Table of n, a(n) for n = 0..50</a> %e A321446 The a(3) = 10 matrices: %e A321446 [1 1] [1 1] [1 0] [0 1] %e A321446 [1 0] [0 1] [1 1] [1 1] %e A321446 . %e A321446 [1 0 0] [1 0 0] [0 1 0] [0 1 0] [0 0 1] [0 0 1] %e A321446 [0 1 0] [0 0 1] [1 0 0] [0 0 1] [1 0 0] [0 1 0] %e A321446 [0 0 1] [0 1 0] [0 0 1] [1 0 0] [0 1 0] [1 0 0] %t A321446 prs2mat[prs_]:=Table[Count[prs,{i,j}],{i,Union[First/@prs]},{j,Union[Last/@prs]}]; %t A321446 Table[Length[Select[Subsets[Tuples[Range[n],2],{n}],And[Union[First/@#]==Range[Max@@First/@#],Union[Last/@#]==Range[Max@@Last/@#],UnsameQ@@prs2mat[#],UnsameQ@@Transpose[prs2mat[#]]]&]],{n,6}] %o A321446 (PARI) \\ Q(m, n, wf) defined in A321588. %o A321446 seq(n)={my(R=vectorv(n,m,Q(m,n,w->1 + y^w + O(y*y^n)))); for(i=2, #R, R[i] -= i*R[i-1]); Vec(1 + vecsum(vecsum(R)))} \\ _Andrew Howroyd_, Jan 24 2024 %Y A321446 Cf. A000612, A007716, A049311, A101370, A120733, A135589, A283877, A316980, A319559, A321515, A321586, A321587, A321588, A369285. %K A321446 nonn %O A321446 0,3 %A A321446 _Gus Wiseman_, Nov 13 2018 %E A321446 a(7) onwards from _Andrew Howroyd_, Jan 20 2024