cp's OEIS Frontend

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.

A086264 Number of real {0,1} n X n matrices having determinant=1.

Original entry on oeis.org

1, 1, 3, 84, 10020, 4851360, 9240051240, 67745781734400, 1883481284085791040
Offset: 0

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Author

Hugo Pfoertner, Oct 05 2003

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := Module[{M, iter, cnt = 0}, M = Table[a[i, j], {i, 1, n}, {j, 1, n}]; iter = Thread[{Flatten[M], 0, 1}]; Do[If[Det[M] == 1, cnt++], Evaluate[Sequence @@ iter]]; cnt];
    Do[Print[n, " ", a[n]], {n, 1, 4}] (* Jean-François Alcover, Dec 09 2018 *)

Extensions

a(0)=1 prepended by Alois P. Heinz, Jun 18 2022
a(7) from Minfeng Wang, Feb 09 2023
a(8) from Minfeng Wang, Apr 26 2024