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A268996 Number of 2 X n binary arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once. 1
4, 13, 35, 103, 278, 763, 2037, 5421, 14264, 37321, 97015, 250963, 646250, 1657719, 4237481, 10798553, 27442092, 69563653, 175938699, 444060607, 1118668286, 2813233523, 7063416349, 17708464645, 44335423456, 110857865665, 276863340767 (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) = 2*a(n-1) + 5*a(n-2) - 4*a(n-3) - 11*a(n-4) - 6*a(n-5) - a(n-6).

Empirical g.f.: x*(4 + 5*x - 11*x^2 - 16*x^3 - 7*x^4 - x^5) / ((1 + x)^2*(1 - 2*x - x^2)^2). - Colin Barker, Jan 18 2019

EXAMPLE

Some solutions for n=4:

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

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

CROSSREFS

Row 2 of A268995.

Sequence in context: A317781 A271358 A306349 * A270988 A272556 A173723

Adjacent sequences:  A268993 A268994 A268995 * A268997 A268998 A268999

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 17 2016

STATUS

approved

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Last modified September 18 12:13 EDT 2021. Contains 347527 sequences. (Running on oeis4.)