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A297427 Number of n X 4 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 2 neighboring 1s. 1
1, 12, 26, 42, 183, 513, 1085, 3332, 9744, 23836, 65693, 187681, 491757, 1322824, 3682514, 9913750, 26662827, 73102697, 198448393, 535843320, 1459128416, 3966961416, 10743629897, 29183372609, 79314611625, 215140998420 (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) + 12*a(n-3) + 2*a(n-4) + 2*a(n-5) - 7*a(n-6) - a(n-7).

Empirical g.f.: x*(1 + 11*x + 14*x^2 + 4*x^3 - 5*x^4 - 8*x^5 - x^6) / (1 - x - 12*x^3 - 2*x^4 - 2*x^5 + 7*x^6 + x^7). - Colin Barker, Feb 28 2019

EXAMPLE

Some solutions for n=5:

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

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

..0..0..0..0. .0..0..0..0. .0..0..0..0. .0..0..0..0. .0..0..0..0

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

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

CROSSREFS

Column 4 of A297431.

Sequence in context: A184826 A119412 A105814 * A211115 A232936 A274897

Adjacent sequences:  A297424 A297425 A297426 * A297428 A297429 A297430

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 30 2017

STATUS

approved

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Last modified August 8 19:29 EDT 2020. Contains 336298 sequences. (Running on oeis4.)