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A307164 Maximum number of intercalates in a diagonal Latin square of order n. 8
0, 0, 0, 12, 4, 9, 30, 112, 72 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

An intercalate is a 2 X 2 subsquare of a Latin square.

0 <= A307163(n) <= A307164(n) <= A092237(n). - Eduard I. Vatutin, Sep 21 2020

a(10) >= 93, a(11) >= 94, a(12) >= 188, a(13) >= 75. - Eduard I. Vatutin, May 31 2021

a(12) >= 252. - Eduard I. Vatutin, Aug 12 2021

LINKS

Table of n, a(n) for n=1..9.

Eduard I. Vatutin, Discussion about properties of diagonal Latin squares at forum.boinc.ru (in Russian).

Eduard I. Vatutin, About the maximum number of intercalates in a diagonal Latin squares of order 9 (in Russian).

Eduard I. Vatutin, Proving list (best known examples).

Eduard Vatutin, Alexey Belyshev, Natalia Nikitina, and Maxim Manzuk, Evaluation of Efficiency of Using Simple Transformations When Searching for Orthogonal Diagonal Latin Squares of Order 10, High-Performance Computing Systems and Technologies in Sci. Res., Automation of Control and Production (HPCST 2020), Communications in Comp. and Inf. Sci. book series (CCIS, Vol. 1304) Springer, Cham (2020), 127-146.

Eduard I. Vatutin, Natalia N. Nikitina, and Maxim O. Manzuk, First results of an experiment on studying the properties of DLS of order 9 in the volunteer distributed computing projects Gerasim@Home and RakeSearch (in Russian).

Index entries for sequences related to Latin squares and rectangles.

EXAMPLE

From Eduard I. Vatutin, May 31 2021: (Start)

One of the best known diagonal Latin squares of order n=5

  0 1 2 3 4

  4 2 0 1 3

  1 4 3 2 0

  3 0 1 4 2

  2 3 4 0 1

has 4 intercalates:

  . . 2 3 .   . . . . .   . . . . .   . . . . .

  . . . . .   . . 0 . 3   . . . . .   . . . . .

  . . 3 2 .   . . 3 . 0   1 . 3 . .   . 4 3 . .

  . . . . .   . . . . .   3 . 1 . .   . . . . .

  . . . . .   . . . . .   . . . . .   . 3 4 . .

so a(5)=4. (End)

CROSSREFS

Cf. A307163, A092237.

Sequence in context: A139358 A004477 A328285 * A181829 A339467 A199693

Adjacent sequences:  A307161 A307162 A307163 * A307165 A307166 A307167

KEYWORD

nonn,more,hard

AUTHOR

Eduard I. Vatutin, Mar 27 2019

EXTENSIONS

a(9) added by Eduard I. Vatutin, Sep 21 2020

STATUS

approved

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Last modified January 20 08:54 EST 2022. Contains 350471 sequences. (Running on oeis4.)