The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A321446 Number of (0,1)-matrices with n ones, no zero rows or columns, and distinct rows and columns. 7
 1, 1, 2, 10, 72, 624, 6522, 80178, 1129368, 17917032, 316108752, 6138887616, 130120838400, 2989026225696, 73964789192400, 1961487062520720, 55495429438186920, 1668498596700706440, 53122020640948010640, 1785467619718933936560, 63175132023953553400440 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Andrew Howroyd, Table of n, a(n) for n = 0..50 EXAMPLE The a(3) = 10 matrices: [1 1] [1 1] [1 0] [0 1] [1 0] [0 1] [1 1] [1 1] . [1 0 0] [1 0 0] [0 1 0] [0 1 0] [0 0 1] [0 0 1] [0 1 0] [0 0 1] [1 0 0] [0 0 1] [1 0 0] [0 1 0] [0 0 1] [0 1 0] [0 0 1] [1 0 0] [0 1 0] [1 0 0] MATHEMATICA prs2mat[prs_]:=Table[Count[prs, {i, j}], {i, Union[First/@prs]}, {j, Union[Last/@prs]}]; 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}] PROG (PARI) \\ Q(m, n, wf) defined in A321588. 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 CROSSREFS Cf. A000612, A007716, A049311, A101370, A120733, A135589, A283877, A316980, A319559, A321515, A321586, A321587, A321588, A369285. Sequence in context: A245834 A271214 A366241 * A111554 A177384 A354288 Adjacent sequences: A321443 A321444 A321445 * A321447 A321448 A321449 KEYWORD nonn AUTHOR Gus Wiseman, Nov 13 2018 EXTENSIONS a(7) onwards from Andrew Howroyd, Jan 20 2024 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 19 18:05 EDT 2024. Contains 371798 sequences. (Running on oeis4.)