A221257 Number of 3Xn arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor, with no occupancy greater than 2

0, 16, 30, 2116, 22268, 488601, 7356420, 132273001, 2175160988, 37343243536, 627439570380, 10652755988736, 179923226827008, 3046558564618321, 51520912019433840, 871812703964410321, 14747896839403221578

Offset

1,2

Comments

Row 3 of A221255

Links

R. H. Hardin, Table of n, a(n) for n = 1..36

Formula

Empirical: a(n) = 21*a(n-1) +21*a(n-2) -1891*a(n-3) +4713*a(n-4) +31527*a(n-5) -98973*a(n-6) -92217*a(n-7) +299577*a(n-8) -27117*a(n-9) +103383*a(n-10) -393*a(n-11) +6211*a(n-12) +69*a(n-13) +69*a(n-14) +a(n-15) for n>18

Example

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

Crossrefs

Sequence in context: A145581 A186453 A129617 * A194122 A257349 A167997

Adjacent sequences: A221254 A221255 A221256 * A221258 A221259 A221260

Keyword

nonn

Author

R. H. Hardin Jan 06 2013

Status

approved