A297375 Number of 2 X n 0..1 arrays with every 1 horizontally or antidiagonally adjacent to 0, 1 or 2 neighboring 1s.

4, 16, 57, 208, 765, 2807, 10294, 37759, 138506, 508054, 1863591, 6835838, 25074539, 91975917, 337376860, 1237532061, 4539391360, 16650941468, 61077318469, 224037712140, 821792732873, 3014417927011, 11057186411122, 40558865522523

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) + a(n-2) + 5*a(n-3) + a(n-4) + a(n-5) - a(n-6) - a(n-7).

Empirical g.f.: x*(1 + x + x^2)*(4 + x^2 - x^4) / ((1 + x^2)*(1 - 3*x - 2*x^2 - 2*x^3 + x^4 + x^5)). - Colin Barker, Feb 27 2019

Example

Some solutions for n=5:
..1..0..0..1..1. .1..1..0..1..0. .0..1..0..0..1. .1..1..0..1..0
..1..1..0..0..0. .0..1..0..1..1. .1..1..1..1..0. .1..1..1..0..0

Crossrefs

Row 2 of A297374.

Sequence in context: A122032 A197674 A297220 * A283124 A282393 A034514

Adjacent sequences: A297372 A297373 A297374 * A297376 A297377 A297378

Keyword

nonn

Author

R. H. Hardin, Dec 29 2017

Status

approved