A297397 - OEIS

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

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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