A207847 Number of 4 X n 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 0 and 1 1 1 vertically.

10, 100, 240, 780, 2320, 7140, 21600, 65980, 200400, 610740, 1857520, 5656380, 17211840, 52396900, 159466800, 485403660, 1477389520, 4496881380, 13687155360, 41660429500, 126802853520, 385955704500, 1174746099760, 3575622750780

Offset: 1

Author

R. H. Hardin, Feb 21 2012

Keywords

• nonn

Comments

Row 4 of A207845.

Examples

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

Links

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

Crossrefs

Cf. A207845.

Formula

Empirical: a(n) = a(n-1) + 6*a(n-2) + a(n-3) - a(n-4) for n>5.

Empirical g.f.: 10*x*(1 + 9*x + 8*x^2 - 7*x^3 + x^4) / (1 - x - 6*x^2 - x^3 + x^4). - Colin Barker, Jun 25 2018