A207250 Number of n X 4 0..1 arrays avoiding 0 0 1 and 1 0 1 horizontally and 0 1 0 and 1 0 1 vertically.

8, 64, 216, 940, 3776, 15652, 64176, 263976, 1084380, 4456764, 18314496, 75265524, 309304372, 1271098480, 5223614592, 21466618480, 88217749664, 362533690524, 1489843800060, 6122560903368, 25160860321572, 103399362536912

Offset: 1

Author

R. H. Hardin, Feb 16 2012

Keywords

• nonn

Comments

Column 4 of A207254.

Examples

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

Links

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

Crossrefs

Cf. A207254.

Formula

Empirical: a(n) = 2*a(n-1) + 7*a(n-2) + 2*a(n-3) + 13*a(n-4) + 27*a(n-5) + 8*a(n-6) - 4*a(n-7) - 4*a(n-8) - 2*a(n-9) + a(n-10).

Empirical g.f.: 4*x*(2 + 12*x + 8*x^2 + 11*x^3 + 38*x^4 + 10*x^5 - 10*x^6 - 6*x^7 - 4*x^8 + 2*x^9) / (1 - 2*x - 7*x^2 - 2*x^3 - 13*x^4 - 27*x^5 - 8*x^6 + 4*x^7 + 4*x^8 + 2*x^9 - x^10). - Colin Barker, Jun 21 2018