A183445 Number of n X 4 binary arrays with every 1 having exactly two king-move neighbors equal to 1.

1, 13, 30, 72, 283, 831, 2399, 7761, 23840, 72396, 225569, 696929, 2144537, 6635889, 20510002, 63318408, 195704391, 604826763, 1868678179, 5774848073, 17846507936, 55148861000, 170427655945, 526681961257, 1627610746225, 5029867948101

Offset

1,2

Comments

Column 4 of A183450.

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + a(n-2) + 5*a(n-3) - 18*a(n-4) - 16*a(n-5) + 7*a(n-6) + 3*a(n-7) + a(n-8) - a(n-9).

Empirical g.f.: x*(1 + x)*(1 + 9*x - 19*x^2 - 17*x^3 + 7*x^4 + 3*x^5 + x^6 - x^7) / (1 - 3*x - x^2 - 5*x^3 + 18*x^4 + 16*x^5 - 7*x^6 - 3*x^7 - x^8 + x^9). - Colin Barker, Mar 29 2018

Example

Some solutions for 5 X 4:
..0..1..0..0....1..1..0..0....0..1..1..0....0..1..0..0....0..0..1..0
..1..0..1..0....0..1..0..0....0..0..1..0....1..1..0..0....0..1..1..0
..1..0..1..0....0..0..0..0....0..0..0..0....0..0..0..0....0..0..0..0
..0..1..0..0....1..1..0..0....0..1..0..0....0..1..0..0....1..0..0..0
..0..0..0..0....0..1..0..0....1..1..0..0....0..1..1..0....1..1..0..0

Crossrefs

Cf. A183450.

Sequence in context: A139577 A172463 A329950 * A296124 A299130 A156532

Adjacent sequences: A183442 A183443 A183444 * A183446 A183447 A183448

Keyword

nonn

Author

R. H. Hardin, Jan 04 2011

Status

approved