A297397 Number of 4 X n 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 1 neighboring 1.

1, 20, 57, 126, 700, 2569, 7779, 31081, 117084, 400727, 1478944, 5485580, 19599269, 71231855, 261062287, 945122754, 3430304343, 12504256178, 45424857782, 164983194009, 600231458537, 2182009835511, 7929300624520, 28830589829675

Offset

1,2

Links

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

Formula

Empirical: a(n) = a(n-1) + 3*a(n-2) + 24*a(n-3) + 11*a(n-4) - 21*a(n-5) - 67*a(n-6) - 9*a(n-7) - 45*a(n-8).

Empirical g.f.: x*(1 + 19*x + 34*x^2 - 15*x^3 - 88*x^4 - 76*x^5 - 54*x^6 - 45*x^7) / (1 - x - 3*x^2 - 24*x^3 - 11*x^4 + 21*x^5 + 67*x^6 + 9*x^7 + 45*x^8). - Colin Barker, Feb 28 2019

Example

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

Crossrefs

Row 4 of A297395.

Sequence in context: A216267 A012483 A051872 * A104100 A069132 A124713

Adjacent sequences: A297394 A297395 A297396 * A297398 A297399 A297400

Keyword

nonn

Author

R. H. Hardin, Dec 29 2017

Status

approved