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 1-3 of 3 results.

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

Cf. A086899, A118986, A118989, A118993, A119009.

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

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

Cf. A086906, A088672, A118986, A118991, A119009, A119010.

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

A119008 Number of n X n real symmetric (0,1)-matrices with determinant = 1.

Original entry on oeis.org

1, 1, 4, 268, 9456, 301306, 24846368, 8946957244, 4175660906560, 2421067614753916
Offset: 1

Views

Author

Giovanni Resta, May 08 2006

Keywords

Crossrefs

Cf. A086264, A086899, A086900, A086906, A118998, A119002, A119009.

Extensions

a(8)-a(10) from Max Alekseyev, Jun 17 2025
Showing 1-3 of 3 results.

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

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