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A296390 Number of n X 2 0..1 arrays with each 1 horizontally, vertically or antidiagonally adjacent to 1 or 3 neighboring 1s. 1
2, 6, 11, 28, 63, 139, 328, 735, 1684, 3853, 8750, 20021, 45627, 104068, 237541, 541649, 1235897, 2819380, 6431345, 14672588, 33470945, 76356833, 174191649, 397374570, 906523725, 2068021039, 4717711395, 10762383681, 24551876711 (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) = a(n-1) + 2*a(n-2) + 2*a(n-3) - a(n-4) + 4*a(n-5) - a(n-6) - 4*a(n-7) + a(n-9).

Empirical g.f.: x*(2 + 4*x + x^2 + x^3 + 3*x^4 - 4*x^5 - 4*x^6 + x^7 + x^8) / (1 - x - 2*x^2 - 2*x^3 + x^4 - 4*x^5 + x^6 + 4*x^7 - x^9). - Colin Barker, Feb 23 2019

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

CROSSREFS

Column 2 of A296396.

Sequence in context: A184884 A275222 A165821 * A135048 A189319 A268501

Adjacent sequences:  A296387 A296388 A296389 * A296391 A296392 A296393

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 11 2017

STATUS

approved

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Last modified May 24 06:53 EDT 2019. Contains 323529 sequences. (Running on oeis4.)