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A268744 Number of n X 2 binary arrays with some element plus some horizontally or vertically adjacent neighbor totalling two no more than once. 2
4, 11, 32, 89, 244, 659, 1760, 4657, 12228, 31899, 82752, 213641, 549236, 1406755, 3591232, 9140833, 23204612, 58765099, 148496608, 374496953, 942729588, 2369172915, 5944748064, 14895231121, 37272007108, 93149401019, 232527917312 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A268750.

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) - 2*a(n-2) - 4*a(n-3) - a(n-4).

Empirical g.f.: x*(4 - 5*x - 4*x^2 - x^3) / (1 - 2*x - x^2)^2. - Colin Barker, Mar 21 2018

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Cf. A268750.

Sequence in context: A155962 A027153 A034754 * A038747 A052545 A183114

Adjacent sequences:  A268741 A268742 A268743 * A268745 A268746 A268747

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 12 2016

STATUS

approved

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Last modified May 26 18:02 EDT 2018. Contains 304628 sequences. (Running on oeis4.)