A208554 Number of nX7 0..1 arrays avoiding 0 0 0 and 0 0 1 horizontally and 0 0 1 and 0 1 1 vertically.

42, 1764, 10710, 65025, 221340, 753424, 1913940, 4862025, 10332630, 21958596, 41363322, 77915929, 134523480, 232257600, 375406920, 606784689, 931373730, 1429596100, 2104920510, 3099260241, 4409811252, 6274540944, 8675694300

Offset: 1

Author

R. H. Hardin Feb 28 2012

Keywords

• nonn

Comments

Column 7 of A208555

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210
• Robert Israel, Maple-assisted proof of formula

Formula

Empirical: a(n) = 2*a(n-1) +6*a(n-2) -14*a(n-3) -14*a(n-4) +42*a(n-5) +14*a(n-6) -70*a(n-7) +70*a(n-9) -14*a(n-10) -42*a(n-11) +14*a(n-12) +14*a(n-13) -6*a(n-14) -2*a(n-15) +a(n-16).

Empirical formula verified (see link). - Robert Israel, Sep 27 2018