A197244 Number of n X 2 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 0,0,1,1,1 for x=0,1,2,3,4.

2, 4, 8, 16, 40, 80, 192, 400, 936, 1984, 4576, 9824, 22408, 48560, 109888, 239728, 539432, 1182432, 2649952, 5828544, 13024648, 28717648, 64040768, 141448528, 314965928, 696544000, 1549366240, 3429474848, 7622621832, 16883244016

Offset: 1

Author

R. H. Hardin, Oct 12 2011

Keywords

• nonn

Comments

Every 0 is next to 0 0's, every 1 is next to 1 0's, every 2 is next to 2 1's, every 3 is next to 3 1's, every 4 is next to 4 1's.

Column 2 of A197250.

Examples

			Some solutions for n=4:
..1..0....1..0....1..2....2..1....0..1....1..2....1..0....1..0....2..1....2..1
..1..2....2..1....0..1....1..0....1..3....0..1....3..1....2..1....1..0....1..0
..0..1....0..1....1..2....1..2....3..1....1..1....1..3....2..1....1..1....2..1
..1..2....1..2....1..0....0..1....1..0....1..0....0..1....1..0....0..1....0..1
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200

Crossrefs

Cf. A197250.

Formula

Empirical: a(n) = 4*a(n-2) +2*a(n-3) +a(n-4) -2*a(n-5).

Empirical g.f.: 2*x*(1 - x)*(1 + x)^3 / (1 - 4*x^2 - 2*x^3 - x^4 + 2*x^5). - Colin Barker, May 11 2018