A203280 Number of n X 3 binary arrays with every element neighboring horizontally or vertically both a 0 and a 1.

0, 4, 28, 64, 372, 1444, 6528, 28900, 127412, 565504, 2499460, 11062276, 48938240, 216501796, 957836180, 4237489216, 18747036420, 82938240100, 366925158784, 1623305328100, 7181627028276, 31772071235584, 140562083391108

Offset

1,2

Comments

Column 3 of A203285.

Links

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

Formula

Empirical: a(n) = 5*a(n-1) -13*a(n-3) -a(n-4) +44*a(n-5) -26*a(n-6) +12*a(n-8) -8*a(n-9).

Empirical g.f.: 4*x^2*(1 + 2*x - 19*x^2 + 26*x^3 - 12*x^4 - 2*x^5 + 8*x^6 - 8*x^7) / ((1 - 5*x + 3*x^2 - 2*x^3)*(1 - 3*x^2 + 10*x^4 - 4*x^6)). - Colin Barker, Jun 04 2018

Example

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

Crossrefs

Cf. A203285.

Sequence in context: A307135 A101002 A197542 * A085024 A085001 A153784

Adjacent sequences: A203277 A203278 A203279 * A203281 A203282 A203283

Keyword

nonn

Author

R. H. Hardin, Dec 31 2011

Status

approved