A221324 Number of n X 4 arrays of occupancy after each element stays put or moves to some horizontal or antidiagonal neighbor, with no occupancy greater than 2.

17, 866, 46105, 2460824, 131347807, 7010554450, 374176705928, 19970973695923, 1065911268786396, 56890876705125765, 3036435876484206258, 162063633563069131638, 8649818983278197229631, 461666606875092805859284

Offset

1,1

Comments

Column 4 of A221328.

Links

R. H. Hardin, Table of n, a(n) for n = 1..118

Formula

Empirical: a(n) = 91*a(n-1) -2497*a(n-2) +29072*a(n-3) -168762*a(n-4) +513070*a(n-5) -765950*a(n-6) +359339*a(n-7) +283374*a(n-8) -252113*a(n-9) -12688*a(n-10) +38079*a(n-11) -6354*a(n-12) +289*a(n-13).

Example

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

Crossrefs

Sequence in context: A231778 A355468 A281428 * A124235 A218660 A086265

Adjacent sequences: A221321 A221322 A221323 * A221325 A221326 A221327

Keyword

nonn

Author

R. H. Hardin, Jan 11 2013

Status

approved