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 1-10 of 10 results.

A305570 Number of diagonal Latin squares of order n with the first row in order and at least one orthogonal diagonal mate.

Original entry on oeis.org

1, 0, 0, 2, 4, 0, 256, 632064, 95024976
Offset: 1

Views

Author

Eduard I. Vatutin, Jun 05 2018

Keywords

Crossrefs

Formula

a(n) = A305571(n) / n!.
a(n) = A274171(n) - A305568(n).

Extensions

Name clarified by Andrew Howroyd, Oct 19 2020
a(9) added by Eduard I. Vatutin, Dec 22 2020

A309599 Number of extended self-orthogonal diagonal Latin squares of order n.

Original entry on oeis.org

1, 0, 0, 48, 480, 0, 1290240, 185794560, 8867730493440, 1852743352320000
Offset: 1

Views

Author

Eduard I. Vatutin, Aug 09 2019

Keywords

Comments

A self-orthogonal diagonal Latin square (SODLS) is a diagonal Latin square orthogonal to its transpose. An extended self-orthogonal diagonal Latin square (ESODLS) is a diagonal Latin square that has an orthogonal diagonal Latin square from the same main class. SODLS is a special case of ESODLS.
A333671(n) <= A287762(n) <= a(n) <= A305571(n). - Eduard I. Vatutin, Jun 07 2020
a(10) >= 1852743352320000. - Eduard I. Vatutin, Jul 10 2020

Examples

			The diagonal Latin square
  0 1 2 3 4 5 6 7 8 9
  1 2 0 4 5 7 9 8 6 3
  5 0 1 6 3 9 8 2 4 7
  9 3 5 8 2 1 7 4 0 6
  4 6 3 5 7 8 0 9 2 1
  8 4 6 9 1 3 2 5 7 0
  7 8 9 0 6 4 5 1 3 2
  2 9 4 7 8 0 3 6 1 5
  6 5 7 1 0 2 4 3 9 8
  3 7 8 2 9 6 1 0 5 4
has orthogonal diagonal Latin square
  0 1 2 3 4 5 6 7 8 9
  3 5 9 8 6 2 0 1 4 7
  4 3 8 7 2 1 9 0 5 6
  6 9 3 4 8 0 1 2 7 5
  7 2 0 1 9 3 5 8 6 4
  2 0 1 5 7 6 4 9 3 8
  8 6 4 2 0 9 7 5 1 3
  1 7 6 0 5 4 8 3 9 2
  9 8 5 6 1 7 3 4 2 0
  5 4 7 9 3 8 2 6 0 1
from the same main class.
		

Crossrefs

Extensions

a(9) calculated by Eduard I. Vatutin, Dec 08 2020, independently checked by Oleg S. Zaikin, Dec 16 2024, added by Eduard I. Vatutin, Jan 30 2025
a(10) added by Eduard I. Vatutin, Oleg S. Zaikin, Jan 30 2025

A287695 Maximum number of diagonal Latin squares with the first row in ascending order that can be orthogonal to a given diagonal Latin square of order n.

Original entry on oeis.org

1, 0, 0, 1, 1, 0, 3, 824, 614
Offset: 1

Views

Author

Eduard I. Vatutin, May 30 2017

Keywords

Comments

A Latin square is normalized if in the first row elements come in increasing order. Any diagonal Latin square orthogonal to a given one can be normalized by renaming its elements (which does not break diagonality and orthogonality). - Max Alekseyev, Dec 07 2019
For all orders n>3 there are diagonal Latin squares without orthogonal mates (also known as bachelor squares), so the minimum number of diagonal Latin squares that can be orthogonal to the same diagonal Latin square is zero. For order n=1 the single square is orthogonal to itself. For n=2 and n=3 diagonal Latin squares do not exist (see A274171). For n=6 orthogonal diagonal Latin squares do not exist (see A305571), so a(6)=0. - Eduard I. Vatutin, May 03 2021
a(n) >= A328873(n) - 1. - Eduard I. Vatutin, Mar 29 2021
a(10) >= 10 (Updated). - Eduard I. Vatutin, Apr 27 2018
a(11) >= 32462. - Eduard I. Vatutin from T. Brada, Mar 11 2021
a(12) >= 3855983322. The result belongs to DLS, which has 30192 diagonal transversals. Calculations performed by a volunteer. - Natalia Makarova, Tomáš Brada, Nov 11 2021
a(13) >= 248703. - Natalia Makarova, Tomáš Brada, Apr 29 2021
a(14) >= 307662. - Natalia Makarova, Alex Chernov, Harry White, May 21 2021
a(16) >= 1658880, a(17) >= 2453352, a(18) >= 96, a(19) >= 1383, a(20) >= 995328, a(21) >= 995328, a(22) >= 432000, a(23) >= 525, a(24) >= 345600, a(25) >= 345600, a(26) >= 48, a(27) >= 345600, a(28) >= 663552, a(29) >= 663552, a(30) >= 40320. For values up to a(100), see the specified link "New boundaries for maximum number of normalized orthogonal diagonal Latin squares to one diagonal Latin square". - Natalia Makarova, Alex Chernov, Harry White, Dec 06 2021

Examples

			From _Eduard I. Vatutin_, Mar 29 2021: (Start)
One of the best existing diagonal Latin squares of order 7
  0 1 2 3 4 5 6
  2 3 1 5 6 4 0
  5 6 4 0 1 2 3
  4 0 6 2 3 1 5
  6 2 0 1 5 3 4
  1 5 3 4 0 6 2
  3 4 5 6 2 0 1
has 3 orthogonal mates
  0 1 2 3 4 5 6   0 1 2 3 4 5 6   0 1 2 3 4 5 6
  5 6 4 0 1 2 3   3 4 5 6 2 0 1   6 2 0 1 5 3 4
  1 5 3 4 0 6 2   4 0 6 2 3 1 5   3 4 5 6 2 0 1
  6 2 0 1 5 3 4   2 3 1 5 6 4 0   1 5 3 4 0 6 2
  3 4 5 6 2 0 1   5 6 4 0 1 2 3   2 3 1 5 6 4 0
  2 3 1 5 6 4 0   6 2 0 1 5 3 4   4 0 6 2 3 1 5
  4 0 6 2 3 1 5   1 5 3 4 0 6 2   5 6 4 0 1 2 3
so a(7)=3. (End)
		

Crossrefs

Extensions

Definition corrected by Max Alekseyev, Dec 07 2019
a(9) added by Eduard I. Vatutin, Dec 12 2020
Edited by Max Alekseyev, Apr 01 2022

A330391 Number of main classes of diagonal Latin squares of order n with at least one orthogonal diagonal mate.

Original entry on oeis.org

1, 0, 0, 1, 1, 0, 5, 1105, 75307
Offset: 1

Views

Author

Eduard I. Vatutin, Feb 25 2020

Keywords

Crossrefs

Formula

a(n) = A287764(n) - A337309(n).

Extensions

a(9) added by Eduard I. Vatutin, Dec 12 2020

A287762 Number of self-orthogonal diagonal Latin squares of order n.

Original entry on oeis.org

1, 0, 0, 48, 480, 0, 322560, 46448640, 81587036160, 850065850368000
Offset: 1

Views

Author

Eduard I. Vatutin, May 31 2017

Keywords

Comments

A self-orthogonal diagonal Latin square is a diagonal Latin square orthogonal to its transpose.
A333671(n) <= a(n) <= A309599(n) <= A305571(n). - Eduard I. Vatutin, Apr 26 2020.

Examples

			0 1 2 3 4 5 6 7 8 9
5 2 0 9 7 8 1 4 6 3
9 5 7 1 8 6 4 3 0 2
7 8 6 4 9 2 5 1 3 0
8 9 5 0 3 4 2 6 7 1
3 6 9 5 2 1 7 0 4 8
4 3 1 7 6 0 8 2 9 5
6 7 8 2 5 3 0 9 1 4
2 0 4 6 1 9 3 8 5 7
1 4 3 8 0 7 9 5 2 6
		

Crossrefs

Formula

a(n) = A287761(n)*n!.

Extensions

a(10) from Eduard I. Vatutin, Mar 14 2020
a(10) corrected by Eduard I. Vatutin, Apr 24 2020

A360220 Maximum number of diagonal transversals in an orthogonal diagonal Latin square of order n.

Original entry on oeis.org

1, 0, 0, 4, 5, 0, 27, 120, 333
Offset: 1

Views

Author

Eduard I. Vatutin, Jan 30 2023

Keywords

Comments

An orthogonal diagonal Latin square is a diagonal Latin square that has at least one orthogonal diagonal mate.
a(10) >= 866, a(11) >= 4828, a(12) >= 30192, a(13) >= 131106, a(17) >= 204995269, a(19) >= 11254190082.
For most orders n, at least one diagonal Latin square with the maximal number of diagonal transversals has an orthogonal mate and A287648(n) = a(n). Known exceptions: n=6 and n=10. - Eduard I. Vatutin, Feb 17 2023
Every orthogonal diagonal Latin square is a diagonal Latin square, so A287647(n) <= A354068(n) <= a(n) <= A287648(n). - Eduard I. Vatutin, Mar 04 2023

Crossrefs

A305569 Number of bachelor diagonal Latin squares of order n.

Original entry on oeis.org

0, 0, 0, 0, 480, 92160, 861557760, 300261256888320, 1835082185382168791040
Offset: 1

Views

Author

Eduard I. Vatutin, Jun 05 2018

Keywords

Comments

A bachelor diagonal Latin square is one with no orthogonal mate.

Crossrefs

Formula

a(n) = A305568(n) * n!.
a(n) = A274806(n) - A305571(n).

Extensions

a(9) added by Eduard I. Vatutin, Dec 22 2020

A360223 Maximum number of intercalates in an orthogonal diagonal Latin square of order n.

Original entry on oeis.org

0, 0, 0, 12, 0, 0, 18, 112, 72
Offset: 1

Views

Author

Eduard I. Vatutin, Jan 30 2023

Keywords

Comments

An intercalate is a 2 X 2 subsquare of a Latin square.
An orthogonal diagonal Latin square is a diagonal Latin square that has at least one orthogonal diagonal mate.
a(10) >= 76, a(11) >= 94, a(12) >= 324, a(13) >= 26. - Eduard I. Vatutin, updated Feb 25 2024

Crossrefs

A333671 Number of doubly self-orthogonal diagonal Latin squares of order n.

Original entry on oeis.org

1, 0, 0, 48, 480, 0, 322560, 46448640, 10381271040, 0
Offset: 1

Views

Author

Eduard I. Vatutin, Apr 01 2020

Keywords

Comments

A doubly self-orthogonal diagonal Latin square (DSODLS) is a diagonal Latin square orthogonal to its transpose and antitranspose.
a(n) <= A287762(n) <= A309599(n) <= A305571(n). - Eduard I. Vatutin, Jun 06 2020

Examples

			0 1 2 3 4 5 6 7 8
2 4 3 0 7 6 8 1 5
4 6 7 1 8 2 3 5 0
8 3 5 6 0 7 1 2 4
7 8 1 4 5 3 0 6 2
3 7 0 2 1 8 5 4 6
1 5 4 7 6 0 2 8 3
5 0 6 8 2 1 4 3 7
6 2 8 5 3 4 7 0 1
		

Crossrefs

A360221 Minimum number of intercalates in an orthogonal diagonal Latin square of order n.

Original entry on oeis.org

0, 0, 0, 12, 0, 0, 0, 2, 0
Offset: 1

Views

Author

Eduard I. Vatutin, Jan 30 2023

Keywords

Comments

An intercalate is a 2 X 2 subsquare of a Latin square.
An orthogonal diagonal Latin squares is a diagonal Latin square that has at least one orthogonal diagonal mate.
a(10) <= 1, a(11) = 0, a(12) <= 4, a(13) = 0. - Eduard I. Vatutin, added Jan 30 2023, updated Sep 24 2024

Crossrefs

Showing 1-10 of 10 results.