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A268745 Number of n X 3 binary arrays with some element plus some horizontally or vertically adjacent neighbor totalling two no more than once. 1
7, 32, 143, 623, 2615, 10830, 44067, 177429, 707163, 2796840, 10986379, 42911627, 166777091, 645395334, 2488065863, 9559464281, 36618142447, 139888931680, 533099140807, 2027067051095, 7692165427919, 29135580083054, 110168752548843 (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) = 4*a(n-1) + 8*a(n-2) - 24*a(n-3) - 38*a(n-4) + 4*a(n-5) + 12*a(n-6) - a(n-8).

Empirical g.f.: x*(7 + 4*x - 41*x^2 - 37*x^3 + 13*x^4 + 6*x^5 + x^6 - x^7) / (1 - 2*x - 6*x^2 + x^4)^2. - Colin Barker, Jan 14 2019

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 3 of A268750.

Sequence in context: A213163 A249999 A034360 * A199845 A188179 A050148

Adjacent sequences:  A268742 A268743 A268744 * A268746 A268747 A268748

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 12 2016

STATUS

approved

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Last modified June 25 04:06 EDT 2021. Contains 345451 sequences. (Running on oeis4.)