A228792 Number of n X 4 binary arrays with top left element equal to 1 and no two ones adjacent horizontally or nw-se.

3, 16, 97, 586, 3588, 22060, 135768, 835776, 5145232, 31675616, 195005248, 1200515520, 7390763648, 45499943936, 280112449792, 1724463325696, 10616356983808, 65357745761280, 402363535587328, 2477080763498496

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 8*a(n-1) - 12*a(n-2) + 4*a(n-3) for n>4.

Empirical g.f.: x*(3 - 8*x + 5*x^2 - 10*x^3) / (1 - 8*x + 12*x^2 - 4*x^3). - Colin Barker, Sep 13 2018

Example

Some solutions for n=4:
..1..0..0..1....1..0..0..0....1..0..0..1....1..0..0..0....1..0..0..0
..0..0..0..1....1..0..0..0....1..0..0..1....0..0..0..0....0..0..0..0
..0..0..0..1....0..0..0..0....0..0..0..0....0..0..1..0....0..0..0..0
..1..0..1..0....1..0..1..0....1..0..1..0....1..0..1..0....1..0..0..1

Crossrefs

Column 4 of A228796.

Sequence in context: A157051 A000271 A157016 * A295810 A233203 A074553

Adjacent sequences: A228789 A228790 A228791 * A228793 A228794 A228795

Keyword

nonn

Author

R. H. Hardin, Sep 04 2013

Status

approved