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 1-7 of 7 results.

A118986 Number of different values taken by the permanent of a symmetric real (0,1)-matrix of order n.

Original entry on oeis.org

1, 2, 3, 6, 14, 46, 176, 908, 5802, 44053
Offset: 0

Views

Author

Giovanni Resta, May 08 2006

Keywords

Links

Crossrefs

Cf. A087983, A118985, A118987, A118988.
Cf. A006125 (number of symmetric real (0,1)-matrices of order (n-1)).

Extensions

a(8) from Minfeng Wang, Jun 12 2024
a(0)=1 prepended by Alois P. Heinz, Jun 12 2024
a(9) from Minfeng Wang, Jun 18 2024

A118993 Number of real n X n symmetric (+1,-1) matrices with nonzero permanent.

Original entry on oeis.org

2, 4, 64, 832, 23808, 1725952, 268435456, 64638447616, 33770336417792
Offset: 1

Views

Author

Giovanni Resta, May 08 2006

Keywords

Crossrefs

Cf. A086899, A118988, A118991, A118992, A118995, A118999, A119001, A119010.

Extensions

a(8)-a(9) from Max Alekseyev, Jun 18 2025

A118995 Number of real n X n symmetric (+1,-1) matrices with positive permanent.

Original entry on oeis.org

1, 4, 32, 592, 11904, 1192384, 134217728, 41896879104, 16885168208896
Offset: 1

Views

Author

Giovanni Resta, May 08 2006

Keywords

Crossrefs

Cf. A086900, A118988, A118999, A118993, A118994, A118999, A119001, A119010.

Formula

a(n) = A118993(n) - A118999(n). For odd n, a(n) = A118999(n) = A118993(n)/2. - Max Alekseyev, Jun 18 2025

Extensions

a(8)-a(9) from Max Alekseyev, Jun 18 2025

A118999 Number of real n X n symmetric (+1,-1) matrices with negative permanent.

Original entry on oeis.org

1, 0, 32, 240, 11904, 533568, 134217728, 22741568512, 16885168208896
Offset: 1

Views

Author

Giovanni Resta, May 08 2006

Keywords

Crossrefs

Cf. A118988, A118997, A118999, A118993, A118994, A118995, A119001, A119010.

Formula

a(n) = A118993(n) - A118995(n). For odd n, a(n) = A118995(n) = A118993(n)/2. - Max Alekseyev, Jun 18 2025

Extensions

a(1) corrected and a(8)-a(9) added by Max Alekseyev, Jun 18 2025

A119001 Minimal permanent of real n X n symmetric (+1,-1) matrices.

Original entry on oeis.org

-1, 0, -6, -8, -120, -96, -5040, -4320, -362880
Offset: 1

Views

Author

Giovanni Resta, May 08 2006

Keywords

Crossrefs

Cf. A118988, A118993, A118995, A118999, A119000, A119010.

Formula

For odd n, a(n) = -n!. - Max Alekseyev, Jun 18 2025

A119010 Number of symmetric n X n (+1,-1)-matrices over the reals with zero permanent.

Original entry on oeis.org

0, 4, 0, 192, 8960, 371200, 0, 4081029120, 1414035671040
Offset: 1

Views

Author

Giovanni Resta, May 08 2006

Keywords

Crossrefs

Cf. A086906, A088672, A118988, A118989, A118990, A118993, A118995, A118999, A119001.

Extensions

a(8)-a(9) from Max Alekseyev, Jun 18 2025

A118987 Number of different values taken by the determinant of a symmetric real (+1,-1)-matrix of order n.

Original entry on oeis.org

1, 2, 2, 3, 5, 7, 11, 19, 40, 91, 214
Offset: 0

Views

Author

Giovanni Resta, May 08 2006

Keywords

Links

Crossrefs

Cf. A089472, A118988, A118985.
Cf. A006125 (number of symmetric real (+1,-1)-matrices of order (n-1)).

Extensions

a(0)=1 prepended by Alois P. Heinz, Mar 16 2019
a(8) from Minfeng Wang, Jun 10 2024
a(9)-a(10) from Minfeng Wang, Jun 12 2024
Showing 1-7 of 7 results.

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

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