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A281124 Number of n X 2 0..2 arrays with no element equal to more than one of its horizontal, vertical and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards. 1
0, 2, 28, 208, 1364, 8354, 48992, 278966, 1554744, 8524848, 46147848, 247246206, 1313446848, 6927856426, 36320588564, 189426835088, 983467437564, 5085683787674, 26206495324448, 134618732560222, 689572430485168 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

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

FORMULA

Empirical: a(n) = 8*a(n-1) - 8*a(n-2) - 30*a(n-3) - 24*a(n-4) - 8*a(n-5) - a(n-6).

Empirical g.f.: 2*x^2*(1 + x)*(1 + 5*x - 5*x^2 - 3*x^3) / (1 - 4*x - 4*x^2 - x^3)^2. - Colin Barker, Feb 15 2019

EXAMPLE

Some solutions for n=4:

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

..1..0. .1..0. .0..2. .1..0. .1..2. .0..2. .1..2. .1..2. .0..2. .0..1

..1..2. .1..2. .1..2. .0..2. .2..0. .0..1. .0..2. .1..1. .1..2. .2..2

..0..2. .0..0. .1..2. .0..1. .2..0. .1..2. .0..0. .2..0. .2..1. .0..2

CROSSREFS

Column 2 of A281129.

Sequence in context: A001798 A123787 A035601 * A244721 A001759 A243475

Adjacent sequences:  A281121 A281122 A281123 * A281125 A281126 A281127

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 15 2017

STATUS

approved

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Last modified October 13 16:10 EDT 2019. Contains 327966 sequences. (Running on oeis4.)