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A297375 Number of 2 X n 0..1 arrays with every 1 horizontally or antidiagonally adjacent to 0, 1 or 2 neighboring 1s. 1
4, 16, 57, 208, 765, 2807, 10294, 37759, 138506, 508054, 1863591, 6835838, 25074539, 91975917, 337376860, 1237532061, 4539391360, 16650941468, 61077318469, 224037712140, 821792732873, 3014417927011, 11057186411122, 40558865522523 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

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

Empirical g.f.: x*(1 + x + x^2)*(4 + x^2 - x^4) / ((1 + x^2)*(1 - 3*x - 2*x^2 - 2*x^3 + x^4 + x^5)). - Colin Barker, Feb 27 2019

EXAMPLE

Some solutions for n=5:

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

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

CROSSREFS

Row 2 of A297374.

Sequence in context: A122032 A197674 A297220 * A283124 A282393 A034514

Adjacent sequences:  A297372 A297373 A297374 * A297376 A297377 A297378

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 29 2017

STATUS

approved

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Last modified January 22 07:39 EST 2020. Contains 331139 sequences. (Running on oeis4.)