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A281201 Number of n X 4 0..1 arrays with no element equal to more than one of its horizontal and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards. 1
2, 28, 98, 270, 676, 1588, 3604, 7960, 17254, 36848, 77776, 162610, 337292, 694982, 1423852, 2902806, 5892558, 11916410, 24017514, 48262212, 96719706, 193358890, 385702166, 767826768, 1525708160, 3026506470, 5994196442, 11854696726 (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) + 3*a(n-2) - 4*a(n-3) - 6*a(n-4) + 2*a(n-5) + 4*a(n-6) - a(n-8).

Empirical g.f.: 2*x*(1 + x)*(1 + 11*x + 7*x^2 - 8*x^3 - 9*x^4 + 2*x^6) / (1 - x - 2*x^2 + x^4)^2. - Colin Barker, Feb 16 2019

EXAMPLE

Some solutions for n=4:

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

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

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

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

CROSSREFS

Column 4 of A281205.

Sequence in context: A156471 A138964 A200040 * A051958 A123807 A213829

Adjacent sequences:  A281198 A281199 A281200 * A281202 A281203 A281204

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 17 2017

STATUS

approved

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Last modified March 20 20:14 EDT 2019. Contains 321352 sequences. (Running on oeis4.)