A228685 Number of 4 X n binary arrays with no two ones adjacent horizontally, diagonally or antidiagonally.

16, 41, 313, 1152, 6737, 28977, 152048, 699833, 3508329, 16628064, 81753697, 392401121, 1913315024, 9233466953, 44861599897, 217002245696, 1052716150641, 5097234627985, 24711403148208, 119703506867161, 580159930998217

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

Example

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

Crossrefs

Row 4 of A228683.

Sequence in context: A227816 A200408 A280184 * A317761 A318340 A318072

Adjacent sequences: A228682 A228683 A228684 * A228686 A228687 A228688

Keyword

nonn

Author

R. H. Hardin, Aug 30 2013

Status

approved