A206990 Number of nX4 0..1 arrays avoiding 0 0 0 horizontally and 1 1 1 vertically.

13, 169, 840, 6510, 46878, 329952, 2371090, 16939450, 120961040, 864671390, 6178621414, 44150290200, 315500062138, 2254527357770, 16110599565656, 115124947986150, 822671737926942, 5878731842796456, 42008857944366290

Offset: 1

Author

R. H. Hardin Feb 14 2012

Keywords

• nonn

Comments

Column 4 of A206994

Examples

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

Links

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

Formula

Empirical: a(n) = 2*a(n-1) +17*a(n-2) +135*a(n-3) +74*a(n-4) -7*a(n-5) -1496*a(n-6) +492*a(n-7) -890*a(n-8) +4192*a(n-9) -1374*a(n-10) +1082*a(n-11) -3316*a(n-12) +622*a(n-13) +112*a(n-14) +684*a(n-15) -125*a(n-16) -42*a(n-17) -43*a(n-18) +7*a(n-19) +2*a(n-20) +a(n-21) for n>23