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A297426 Number of n X 3 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 2 neighboring 1s. 1
1, 7, 14, 22, 68, 163, 320, 782, 1889, 4109, 9474, 22365, 50630, 115709, 268817, 616265, 1410697, 3253586, 7480630, 17161490, 39477589, 90787636, 208528864, 479338273, 1102090695, 2532624372, 5820869563, 13380882748, 30754476169 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

FORMULA

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

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

EXAMPLE

Some solutions for n=5:

..0..1..0. .1..1..1. .1..1..0. .1..1..1. .0..1..0. .0..1..1. .1..1..1

..1..1..1. .0..1..0. .0..1..1. .0..1..0. .1..1..1. .0..1..1. .0..1..0

..0..0..0. .0..0..0. .0..0..0. .0..1..0. .0..0..0. .0..0..0. .0..0..0

..0..1..1. .0..1..1. .0..1..1. .1..0..1. .1..1..1. .0..1..1. .1..1..1

..0..1..1. .0..1..1. .0..1..1. .0..1..0. .0..1..0. .1..1..0. .0..1..0

CROSSREFS

Column 3 of A297431.

Sequence in context: A118502 A190367 A246172 * A036556 A013644 A178894

Adjacent sequences:  A297423 A297424 A297425 * A297427 A297428 A297429

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 30 2017

STATUS

approved

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Last modified October 18 01:39 EDT 2021. Contains 348065 sequences. (Running on oeis4.)