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, 16, 3456, 12931216, 655816458528, 473216230511351044, 4822507485300347026181088, 695298786420085228281048744405924, 1417923660297801516897331705897083237291008

Offset

1,2

Comments

Diagonal of A217028

Links

Table of n, a(n) for n=1..9.

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 * A087519 A367535 A222917

Adjacent sequences: A217018 A217019 A217020 * A217022 A217023 A217024

Keyword

nonn

Author

R. H. Hardin Sep 24 2012

Status

approved