A183685 Number of (n+1) X 7 binary arrays with every 2 X 2 subblock nonsingular.

192, 1360, 8704, 58448, 382848, 2542368, 16748160, 110871040, 731709056, 4838473472, 31954317952, 211206670208, 1395251843712, 9220409667200, 60918293373568, 402541765541504, 2659689937121920, 17574356285235840

Offset: 1

Author

R. H. Hardin, Jan 06 2011

Keywords

• nonn

Comments

Column 6 of A183688.

Examples

			Some solutions for 3 X 7:
..0..1..1..1..0..1..1....1..1..1..1..0..1..1....1..1..0..1..0..1..0
..1..1..0..1..1..0..1....1..0..1..0..1..0..1....0..1..1..1..1..0..1
..0..1..1..1..0..1..1....1..1..1..1..1..1..0....1..0..1..0..1..1..1
		

Links

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

Crossrefs

Cf. A183688.

Formula

Empirical: a(n) = 3*a(n-1) + 48*a(n-2) - 78*a(n-3) - 720*a(n-4) + 612*a(n-5) + 4232*a(n-6) - 1392*a(n-7) - 8192*a(n-8).

Empirical g.f.: 16*x*(12 + 49*x - 287*x^2 - 1123*x^3 + 2127*x^4 + 8058*x^5 - 4668*x^6 - 17344*x^7) / (1 - 3*x - 48*x^2 + 78*x^3 + 720*x^4 - 612*x^5 - 4232*x^6 + 1392*x^7 + 8192*x^8). - Colin Barker, Apr 04 2018