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A261603 Number of permutations of the set {1,2,...,n}^2 such that first coordinates of first floor(n^2/2) elements are nondecreasing and second coordinates of the remaining ceiling(n^2/2) elements are nondecreasing. 1
1, 10, 1944, 15858432, 7763310604800, 338060641751949312000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..6.

FORMULA

a(n) = A261602(n, floor(n^2/2)) = A261602(n, ceiling(n^2/2)).

CROSSREFS

Main diagonal of A261602.

Sequence in context: A160303 A336666 A024138 * A245016 A294174 A177359

Adjacent sequences:  A261600 A261601 A261602 * A261604 A261605 A261606

KEYWORD

nonn,more

AUTHOR

Max Alekseyev, Aug 25 2015

STATUS

approved

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Last modified June 22 14:15 EDT 2021. Contains 345380 sequences. (Running on oeis4.)