A189273 Number of n X n array permutations with each element not moved or moved diagonally or antidiagonally by one.

1, 4, 45, 2704, 670480, 787195249, 4145792570105, 101143260268999524, 11280706205128114909440, 5796399045731034830898691089, 13683583940408484626053574835068160, 148672374145154580465126584170730657054929, 7431065990498975549840519048937892773708604741833

Offset: 1

Author

R. H. Hardin, Apr 19 2011

Keywords

• nonn

Comments

a(n) is a perfect square when n is even. - Pontus von Brömssen, Sep 03 2024

Examples

			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
		

Links

• Pontus von Brömssen, Table of n, a(n) for n = 1..20

Crossrefs

Diagonal of A189280.

Extensions

More terms from Pontus von Brömssen, Sep 03 2024