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 1-6 of 6 results.

A118988 Number of different values taken by the permanent of a symmetric real (+1,-1)-matrix of order n.

Original entry on oeis.org

1, 2, 2, 4, 7, 15, 20, 62, 190, 771, 2073
Offset: 0

Views

Author

Giovanni Resta, May 08 2006

Keywords

Crossrefs

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

Extensions

a(8)-a(9) from Minfeng Wang, Jun 20 2024
a(0)=1 prepended by Alois P. Heinz, Jun 21 2024
a(10) from Minfeng Wang, Sep 21 2024

A118985 Number of different values taken by the determinant of a symmetric real (0,1)-matrix of order n.

Original entry on oeis.org

1, 2, 3, 5, 7, 11, 19, 40, 91, 214, 577
Offset: 0

Views

Author

Giovanni Resta, May 08 2006

Keywords

Crossrefs

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

Extensions

a(0)=1 prepended by Alois P. Heinz, Mar 16 2019
a(8) from Minfeng Wang, Jun 11 2024
a(9) from Minfeng Wang, Jun 12 2024
a(10) from Hugo Pfoertner, Jun 25 2024

A118991 Number of real n X n symmetric (0,1) matrices with nonzero permanent.

Original entry on oeis.org

1, 5, 39, 753, 25887, 1842241, 247531775, 65994415105, 34412945590783
Offset: 1

Views

Author

Giovanni Resta, May 08 2006

Keywords

Crossrefs

Formula

a(n) = 2^(n(n+1)/2) - A118989(n) = 2^A000217(n) - A118989(n) = A006125(n+1) - A118989(n). - Max Alekseyev, Apr 22 2010; corrected by Herman Jamke (hermanjamke(AT)fastmail.fm), Sep 26 2010

Extensions

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

A118998 Minimal determinant of real n X n symmetric (0,1) matrices.

Original entry on oeis.org

0, -1, -2, -3, -5, -9, -32, -56, -128, -320
Offset: 1

Views

Author

Giovanni Resta, May 08 2006

Keywords

Crossrefs

Extensions

a(8)-a(10) from Max Alekseyev, Jun 17 2025

A118989 Number of symmetric n X n (0,1)-matrices over the reals with zero permanent.

Original entry on oeis.org

1, 3, 25, 271, 6881, 254911, 20903681, 2725061631, 771426498049
Offset: 1

Views

Author

Giovanni Resta, May 08 2006

Keywords

Crossrefs

Formula

a(n) = 2^(n*(n+1)/2) - A118991(n) = 2^A000217(n) - A118991(n) = A006125(n+1) - A118991(n). - Max Alekseyev, Apr 22 2010; corrected by Herman Jamke (hermanjamke(AT)fastmail.fm), Sep 26 2010

Extensions

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

A119009 Number of n X n real symmetric (0,1)-matrices with permanent = 1.

Original entry on oeis.org

1, 4, 22, 286, 5126, 190096, 9477868, 923926396, 118222774300
Offset: 1

Views

Author

Giovanni Resta, May 08 2006

Keywords

Crossrefs

Extensions

a(8)-a(9) from Max Alekseyev, Jun 18 2025
Showing 1-6 of 6 results.