A217023 Number of city-block distance 1, pressure limit 2 movements in an nX3 array with each element moving exactly one horizontally or vertically and no element acquiring more than two neighbors

2, 121, 3456, 108900, 3356150, 103754596, 3204762800, 99000846736, 3058191082836, 94469768837136, 2918234843229824, 90146267379942400, 2784679492865603384, 86020644174498694144, 2657236212002608395264

Offset

1,1

Comments

Column 3 of A217028

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 33*a(n-1) -2152*a(n-3) +3498*a(n-4) +26598*a(n-5) -55952*a(n-6) +44616*a(n-8) -17576*a(n-9) for n>10

Example

Some solutions for n=3 (movement: 0=n 1=e 2=s 3=w)
..1..1..2....1..1..2....2..2..3....1..3..2....1..1..2....2..1..3....1..2..3
..2..3..3....0..2..3....2..3..0....0..1..3....1..0..2....0..1..2....2..2..0
..0..1..3....0..0..0....1..3..3....0..0..3....1..3..3....0..3..3....0..3..0

Crossrefs

Sequence in context: A337989 A042799 A281983 * A332112 A074490 A056638

Adjacent sequences: A217020 A217021 A217022 * A217024 A217025 A217026

Keyword

nonn

Author

R. H. Hardin Sep 24 2012

Status

approved