A221135 Number of nX4 arrays of occupancy after each element moves to some horizontal or vertical neighbor, with no occupancy greater than 2

4, 289, 12544, 643204, 31203396, 1539699121, 75512292025, 3709710975721, 182118668668225, 8941989810789025, 439009303948483984, 21553427021714858449, 1058163003670012270144, 51950295646215686851681

Offset

1,1

Comments

Column 4 of A221139

Links

R. H. Hardin, Table of n, a(n) for n = 1..23

Example

Some solutions for n=3
..2..2..2..1....2..1..1..1....1..2..2..0....0..1..2..0....2..2..1..0
..1..0..1..1....2..1..0..1....1..0..1..2....2..2..1..0....0..1..1..1
..1..0..0..1....0..2..1..0....1..1..0..1....0..1..2..1....1..2..0..1

Crossrefs

Sequence in context: A090088 A253233 A242997 * A110816 A112322 A281535

Adjacent sequences: A221132 A221133 A221134 * A221136 A221137 A221138

Keyword

nonn

Author

R. H. Hardin Jan 02 2013

Status

approved