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A189273
Number of n X n array permutations with each element not moved or moved diagonally or antidiagonally by one.
1
1, 4, 45, 2704, 670480, 787195249, 4145792570105, 101143260268999524, 11280706205128114909440, 5796399045731034830898691089, 13683583940408484626053574835068160, 148672374145154580465126584170730657054929, 7431065990498975549840519048937892773708604741833
OFFSET
1,2
COMMENTS
a(n) is a perfect square when n is even. - Pontus von Brömssen, Sep 03 2024
LINKS
Pontus von Brömssen, Table of n, a(n) for n = 1..20
EXAMPLE
Some solutions for 3 X 3:
..0..3..4....0..5..4....4..3..2....0..3..2....0..3..4....0..5..2....0..3..2
..7..2..1....7..2..1....1..0..7....1..8..7....1..2..7....7..6..1....7..4..1
..6..5..8....6..3..8....6..5..8....6..5..4....6..5..8....4..3..8....6..5..8
CROSSREFS
Diagonal of A189280.
Sequence in context: A364656 A102894 A132552 * A288554 A288562 A349866
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 19 2011
EXTENSIONS
More terms from Pontus von Brömssen, Sep 03 2024
STATUS
approved