A186877 Number of (n+2) X 7 0..3 arrays with every 3 X 3 subblock commuting with each horizontal and vertical neighbor 3 X 3 subblock.

104701, 14221, 28984, 100600, 214264, 230224, 260584, 310528, 410080, 683224, 1122832, 1759144, 3352075, 5594230, 8725153, 15545365, 25632073, 40294021, 70802629, 117837190, 187990240, 326143906, 544135555, 875468515, 1502329147

Offset

1,1

Comments

Column 5 of A186881.

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = 2*a(n-1) - a(n-2) + 3*a(n-3) - 6*a(n-4) + 3*a(n-5) + 3*a(n-6) - 3*a(n-7) for n>13.

Empirical g.f.: x*(104701 - 195181*x + 105243*x^2 - 257250*x^3 + 627591*x^4 - 413433*x^5 - 470262*x^6 + 164880*x^7 + 298431*x^8 - 84456*x^9 - 233280*x^10 + 344763*x^12) / ((1 - x)*(1 - x - 3*x^3 + 3*x^4 - 3*x^6)). - Colin Barker, Apr 20 2018

Example

Some solutions for 4 X 7:
..0..0..0..0..0..2..0....2..0..0..0..0..0..2....0..0..0..0..0..2..1
..0..0..0..0..0..0..0....0..0..0..0..0..0..2....2..0..0..0..0..0..2
..1..0..0..0..0..0..0....0..0..0..0..0..0..0....3..2..0..0..0..0..0
..1..2..0..0..0..0..0....0..2..0..0..0..0..0....0..3..2..0..0..0..0

Crossrefs

Cf. A186881.

Sequence in context: A233857 A106024 A174293 * A304283 A138165 A202934

Adjacent sequences: A186874 A186875 A186876 * A186878 A186879 A186880

Keyword

nonn

Author

R. H. Hardin, Feb 28 2011

Status

approved