A184680 Number of (n+1) X 4 binary arrays with every 2 X 2 subblock singular.

76, 544, 3360, 21968, 140816, 909520, 5858896, 37779664, 243525712, 1569965008, 10120785744, 65244856016, 420606054992, 2711476238800, 17479769838928, 112684908266704, 726433311008848, 4683017326649296, 30189489673849680

Offset: 1

Author

R. H. Hardin, Jan 19 2011

Keywords

• nonn

Comments

Column 3 of A184686.

Examples

			Some solutions for 3 X 4:
..0..0..0..0....0..0..0..0....1..0..1..0....0..0..0..0....0..0..1..0
..1..1..0..0....1..0..0..0....0..0..0..0....0..1..0..0....0..0..0..0
..1..1..0..1....0..0..1..1....0..0..0..0....0..1..0..0....0..1..0..0
		

Links

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

Crossrefs

Cf. A184686.

Formula

Empirical: a(n) = 7*a(n-1) + 2*a(n-2) - 40*a(n-3) + 24*a(n-4) + 16*a(n-5).

Empirical g.f.: 4*x*(19 + 3*x - 150*x^2 + 100*x^3 + 64*x^4) / ((1 - 2*x)*(1 - 5*x - 12*x^2 + 16*x^3 + 8*x^4)). - Colin Barker, Apr 14 2018