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A217021
Number of city-block distance 1, pressure limit 2 movements in an n X n array with each element moving exactly one horizontally or vertically and no element acquiring more than two neighbors
0
0, 16, 3456, 12931216, 655816458528, 473216230511351044, 4822507485300347026181088, 695298786420085228281048744405924, 1417923660297801516897331705897083237291008
OFFSET
1,2
COMMENTS
Diagonal of A217028
EXAMPLE
Some solutions for n=3 (movement: 0=n 1=e 2=s 3=w)
..2..1..3....2..3..3....1..2..3....2..3..2....1..3..2....1..1..2....1..2..3
..2..3..0....1..1..3....2..1..0....2..1..0....2..3..2....2..2..3....2..3..0
..1..0..3....1..3..3....1..1..3....0..1..3....0..1..3....0..0..3....0..0..0
CROSSREFS
Sequence in context: A364483 A281821 A003773 * A375121 A087519 A367535
KEYWORD
nonn
AUTHOR
R. H. Hardin Sep 24 2012
STATUS
approved