A221274 Number of n X 4 arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, with every occupancy equal to zero or two.

1, 25, 100, 1089, 6724, 56644, 400689, 3122289, 23049601, 175350564, 1311815961, 9905822784, 74413292944, 560619075025, 4216817073121, 31746204178129, 238880949939076, 1798010762343849, 13531178521076836, 101839561889056996, 766437062965271569

Offset

1,2

Links

R. H. Hardin, Table of n, a(n) for n = 1..21

Formula

Empirical: a(n) = 7*a(n-1) +16*a(n-2) -105*a(n-3) +108*a(n-4) +10*a(n-5) -56*a(n-6) -53*a(n-7) +23*a(n-8) -6*a(n-9) +a(n-10).

Example

Some solutions for n=4:
..0..2..2..0....0..2..2..0....0..0..2..2....0..0..2..0....2..2..2..0
..2..0..0..0....2..0..0..2....2..2..0..0....0..2..2..2....0..2..0..2
..0..2..2..0....2..2..0..2....0..0..2..2....2..0..2..2....0..0..2..0
..0..2..2..2....0..0..2..0....0..2..2..0....0..2..0..0....2..2..0..0

Crossrefs

Column 4 of A221275.

Sequence in context: A016850 A309779 A356533 * A042220 A114254 A042222

Adjacent sequences: A221271 A221272 A221273 * A221275 A221276 A221277

Keyword

nonn

Author

R. H. Hardin, Jan 09 2013

Status

approved