A207084 Number of n X 4 0..1 arrays avoiding 0 0 0 horizontally and 0 0 1 vertically.

13, 169, 1393, 10621, 75221, 518001, 3500117, 23428181, 155913829, 1034324253, 6848794157, 45301138173, 299456026377, 1978795266229, 13073066599357, 86357724891721, 570419071704225, 3767635749133789, 24884750059577649

Offset: 1

Author

R. H. Hardin Feb 15 2012

Keywords

• nonn

Comments

Column 4 of A207088.

Examples

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

Links

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

Crossrefs

Cf. A207088.

Formula

Empirical: a(n) = 11*a(n-1) -11*a(n-2) -195*a(n-3) +361*a(n-4) +1387*a(n-5) -2443*a(n-6) -5105*a(n-7) +6602*a(n-8) +9836*a(n-9) -7666*a(n-10) -9322*a(n-11) +3553*a(n-12) +4167*a(n-13) -507*a(n-14) -741*a(n-15) +25*a(n-16) +51*a(n-17) -a(n-18) -a(n-19).

Formula confirmed by Robert Israel, May 15 2018 (see link).