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.

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

Links

Crossrefs

Cf. A089472, A108150, A118987, A118986, A373915, A373916.
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

A373915 Determinants of symmetric real {0,1}-matrices of order 9 that only occur as positive values.

Original entry on oeis.org

89, 94, 95, 97, 98, 99, 101, 102, 105, 110, 116, 125, 144
Offset: 1

Views

Author

Hugo Pfoertner, Jun 23 2024

Keywords

Comments

The non-occurrence of the corresponding negative determinants causes the difference A089472(9) - A118985(9) = 227 - 214 = 13.
A similar situation already occurs for 7 X 7 matrices, where the 3 determinant values -20, -24, -32 only occur with negative signs.

Links

Crossrefs

Cf. A003432, A089472, A108150, A118985.

A373916 Numbers that are the determinant of real {0,1}-matrices of order 10, but not of symmetric such matrices.

Original entry on oeis.org

253, 268, 274, 294, 304
Offset: 1

Views

Author

Hugo Pfoertner, Jun 25 2024

Keywords

Comments

This property also applies to the corresponding negative values.

Links

Crossrefs

Cf. A003432, A006125, A013588, A089472, A108150, A118985, A373915.
Showing 1-3 of 3 results.

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