A228663 Number of 4 X n binary arrays with top left value 1 and no two ones adjacent horizontally, diagonally or antidiagonally.

8, 12, 140, 416, 2844, 11148, 62368, 275708, 1420076, 6614240, 32897116, 156718796, 767930400, 3694025404, 17985757548, 86879470432, 421850136604, 2041379040012, 9900460336800, 47946203889788, 232416817429420, 1125924852017632

Offset

1,1

Links

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

Formula

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

Empirical g.f.: 4*x*(1 + x)*(2 - 3*x) / (1 - 2*x - 16*x^2 + 7*x^3 + 18*x^4). - Colin Barker, Sep 12 2018

Example

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

Crossrefs

Row 4 of A228660.

Sequence in context: A196077 A067923 A258780 * A076028 A281256 A070476

Adjacent sequences: A228660 A228661 A228662 * A228664 A228665 A228666

Keyword

nonn

Author

R. H. Hardin, Aug 29 2013

Status

approved