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 11 results. Next

A309598 Number of extended self-orthogonal diagonal Latin squares of order n with the first row in ascending order.

Original entry on oeis.org

1, 0, 0, 2, 4, 0, 256, 4608, 24437088, 510566400
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.
A333367(n) <= A287761(n) <= a(n) <= A305570(n). - Eduard I. Vatutin, Jun 07 2020
a(10) >= 510566400. - 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

Formula

From Eduard I. Vatutin, Feb 25 2020: (Start)
a(n) = A287761(n) for 1 <= n <= 6.
a(n) = 4*A287761(n) for 7 <= n <= 8. (End)
a(10) = A309210(10)*A299784(10) because no DSODLS exist for order n=10 and no ESODLS of order n=10 have generalized M-symmetries (automorphisms). - Eduard I. Vatutin, Jul 10 2020

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

A305571 Number of diagonal Latin squares of order n with at least one orthogonal diagonal mate.

Original entry on oeis.org

1, 0, 0, 48, 480, 0, 1290240, 25484820480, 34482663290880
Offset: 1

Views

Author

Eduard I. Vatutin, Jun 05 2018

Keywords

Crossrefs

Formula

a(n) = A305570(n) * n!.
a(n) = A274806(n) - A305569(n).

Extensions

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

A287761 Number of self-orthogonal diagonal Latin squares of order n with the first row in ascending order.

Original entry on oeis.org

1, 0, 0, 2, 4, 0, 64, 1152, 224832, 234255360
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.
A333367(n) <= a(n) <= A309598(n) <= A305570(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) = A287762(n)/n!.
From Eduard I. Vatutin, Mar 14 2020: (Start)
a(i) != A329685(i)*A299784(i)/2 for i=1..9 due to the existence of doubly self-orthogonal diagonal Latin square (DSODLS) and/or generalized symmetries (automorphisms) for some SODLS.
a(10) = A329685(10)*A299784(10)/2 because no DSODLS exist for order n=10 and no SODLS of order n=10 have generalized symmetries (automorphisms). (End)

Extensions

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

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

A349199 a(n) is the number of distinct numbers of diagonal transversals that an orthogonal diagonal Latin square of order n can have.

Original entry on oeis.org

1, 0, 0, 1, 1, 0, 3, 31, 165
Offset: 1

Views

Author

Eduard I. Vatutin, Nov 10 2021

Keywords

Comments

An orthogonal diagonal Latin square is a diagonal Latin square with at least one orthogonal diagonal mate. Since all orthogonal diagonal Latin squares are diagonal Latin squares, a(n) <= A345370(n).
a(10) >= 390, a(11) >= 560, a(12) >= 13429. - Eduard I. Vatutin, Nov 10 2021, updated Jan 29 2023

Examples

			For n=8 the number of diagonal transversals that an orthogonal diagonal Latin square of order 8 may have is 8, 9, 10, 12, 14, 15, 16, 17, 18, 20, 22, 23, 24, 25, 26, 28, 30, 32, 36, 38, 40, 42, 44, 48, 52, 56, 64, 72, 88, 96, or 120. Since there are 31 distinct values, a(8)=31.
		

Crossrefs

A350585 a(n) is the number of distinct numbers of transversals that an orthogonal diagonal Latin square of order n can have.

Original entry on oeis.org

1, 0, 0, 1, 1, 0, 4, 25, 295
Offset: 1

Views

Author

Eduard I. Vatutin, Mar 27 2022

Keywords

Comments

An orthogonal diagonal Latin square is a diagonal Latin square with at least one orthogonal diagonal mate. Since all orthogonal diagonal Latin squares are diagonal Latin squares, a(n) <= A344105(n).
a(10) >= 193, a(11) >= 3588, a(12) >= 10465. - updated by Eduard I. Vatutin, Jan 29 2023

Examples

			For n=8 the number of transversals that an orthogonal diagonal Latin square of order 8 may have is 16, 32, 40, 48, 52, 56, 60, 64, 68, 72, 76, 80, 88, 96, 112, 128, 132, 144, 160, 168, 192, 224, 256, 320, or 384. Since there are 25 distinct values, a(8)=25.
		

Crossrefs

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

A305568 Number of bachelor diagonal Latin squares of order n with the first row in ascending order.

Original entry on oeis.org

0, 0, 0, 0, 4, 128, 170944, 7446955776, 5056994558482608
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) = A305569(n) / n!.
a(n) = A274171(n) - A305570(n).

Extensions

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

A333367 Number of doubly self-orthogonal diagonal Latin squares of order n with the first row in ascending order.

Original entry on oeis.org

1, 0, 0, 2, 4, 0, 64, 1152, 28608, 0
Offset: 1

Views

Author

Eduard I. Vatutin, Mar 17 2020

Keywords

Comments

A doubly self-orthogonal diagonal Latin square (DSODLS) is a diagonal Latin square orthogonal to its transpose and antitranspose.
a(n) <= A287761(n) <= A309598(n) <= A305570(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

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

Showing 1-10 of 11 results. Next