A203177 Number of nX4 0..2 arrays with every 1 immediately preceded by 0 to the left or above, no 0 immediately preceded by a 0, and every 2 immediately preceded by 0 1 to the left or above.

2, 4, 17, 59, 205, 724, 2466, 8948, 30945, 108083, 382615, 1333850, 4692643, 16441939, 57654309, 202490869, 709321155, 2489832932, 8732839148, 30624223891, 107449317301, 376820699674, 1321873641658, 4636665217896, 16263018992261

Offset: 1

Author

R. H. Hardin Dec 30 2011

Keywords

• nonn

Comments

Column 4 of A203181

Examples

			Some solutions for n=5
..0..1..2..0....0..1..2..0....0..1..2..0....0..1..2..0....0..1..0..1
..1..0..1..1....1..0..1..1....1..0..1..2....1..0..1..1....1..0..1..0
..0..1..0..1....0..1..2..0....0..1..2..0....0..1..0..1....0..1..0..1
..1..2..1..0....1..2..0..1....1..0..1..1....1..2..1..0....1..0..1..0
..0..1..0..1....0..1..1..2....0..1..2..0....2..0..2..1....2..1..2..1
		

Links

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

Formula

Empirical: a(n) = 5*a(n-2) +34*a(n-3) +13*a(n-4) -38*a(n-5) -419*a(n-6) -124*a(n-7) +145*a(n-8) +2520*a(n-9) +37*a(n-10) -584*a(n-11) -6715*a(n-12) +1170*a(n-13) +55*a(n-14) +6304*a(n-15) +476*a(n-16) -78*a(n-17) -480*a(n-19)