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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, 1761952269949978269865476096000, 1455735772788406631491292993098686136320000, 241478064611792629237655079290406479536142910750720000000, 10017186663047806334488985920024892176911305625097432121928056832000000000
OFFSET
1,2
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 * A346543 A245016 A294174
KEYWORD
nonn
AUTHOR
Max Alekseyev, Aug 25 2015
EXTENSIONS
a(7)-a(10) from Max Alekseyev, Jul 13 2022
STATUS
approved