A208370 Number of 4 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 0 1 0 vertically.

9, 81, 351, 1953, 9999, 52821, 275769, 1446381, 7572429, 39673377, 207796977, 1088500725, 5701622643, 29865934989, 156441006369, 819457342785, 4292413923915, 22484179383741, 117774808544331, 616918515422625

Offset

1,1

Comments

Row 4 of A208369.

Links

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

Formula

Empirical: a(n) = a(n-1) + 19*a(n-2) + 23*a(n-3) - 26*a(n-4) - 38*a(n-5) + 13*a(n-6) + 15*a(n-7) - 4*a(n-8).

Empirical g.f.: 9*x*(1 + 8*x + 11*x^2 - 16*x^3 - 28*x^4 + 10*x^5 + 15*x^6 - 4*x^7) / ((1 + x)*(1 - 2*x - 17*x^2 - 6*x^3 + 32*x^4 + 6*x^5 - 19*x^6 + 4*x^7)). - Colin Barker, Jul 02 2018

Example

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

Crossrefs

Cf. A208369.

Sequence in context: A208138 A207444 A207428 * A207422 A207737 A221963

Adjacent sequences: A208367 A208368 A208369 * A208371 A208372 A208373

Keyword

nonn

Author

R. H. Hardin, Feb 25 2012

Status

approved