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.

Showing 1-2 of 2 results.

A049475 Number of 2n X 2n matrices whose entries are {0,-1,+1} and whose row sums and column sums are all distinct.

Original entry on oeis.org

1, 4, 39, 2260, 1338614, 8522456190
Offset: 1

Views

Author

Michael Kleber

Keywords

Comments

Matrices differing by taking transpose, multiplying by -1 and permuting rows and columns are regarded as equivalent.

Examples

			A 2 X 2 example: [ 1 1; 0 -1 ].

References

  • It is known (see references) that a (2n+1) X (2n+1) matrix of this form cannot exist.
  • Rainer Bodendiek, Gustav Burosch; Streifzüge durch die Kombinatorik, Aufgaben und Lösungen aus dem Schatz der Mathematik-Olympiaden, (Excursions into Combinatorics) Spektrum Akademischer Verlag, Heidelberg, 1995, ISBN 3-86025-393-X Kapitel: Aufgaben zu Invarianten, Aufgabe 5.30, pp. 250-253.
  • Fred Galvin, posting to sci.math, Date: 1999-09-25 - Solution to the antimagic 0,1,-1 matrix problem.

Links

Crossrefs

Cf. A049526, A049527.

Extensions

Bodendiek-Burosch reference from torsten.sillke(AT)lhsystems.com
a(6) from Denis Cazor, Dec 06 2017

A049526 Number of possible sets {{row sums}, {column sums}} of a 2n X 2n matrix with entries from {0,1,-1} and all row and column sums distinct.

Original entry on oeis.org

2, 6, 22, 94, 458, 2512, 15354, 103436, 758848
Offset: 1

Views

Author

Michael Kleber

Keywords

Comments

It is known that such matrices of size (2n+1) X (2n+1) do not exist.

Crossrefs

Cf. A049475, A049527.
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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