A297391 Number of n X 4 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 1 neighboring 1.

4, 13, 37, 126, 385, 1243, 3924, 12477, 39625, 125780, 399527, 1268481, 4028320, 12791471, 40619227, 128985178, 409588149, 1300636903, 4130132236, 13115120227, 41646681705, 132247843570, 419949219621, 1333536652989, 4234607278278

Offset

1,1

Links

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

Formula

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

Empirical g.f.: x*(4 + 9*x - 5*x^3 - 3*x^4 - 3*x^5 - x^6) / (1 - x - 6*x^2 - 4*x^3 + 3*x^4 + x^5 + 2*x^6 + x^7). - Colin Barker, Feb 28 2019

Example

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

Crossrefs

Column 4 of A297395.

Sequence in context: A077842 A091874 A067633 * A108489 A155375 A155307

Adjacent sequences: A297388 A297389 A297390 * A297392 A297393 A297394

Keyword

nonn

Author

R. H. Hardin, Dec 29 2017

Status

approved