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A317759 Number of nX2 0..1 arrays with every element unequal to 0, 1 or 2 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero. 3
2, 6, 10, 20, 42, 89, 190, 407, 873, 1874, 4024, 8642, 18561, 39866, 85627, 183917, 395034, 848492, 1822474, 3914489, 8407926, 18059375, 38789713, 83316386, 178955184, 384377666, 825604417, 1773314930, 3808901427, 8181135701 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 2 of A317764.

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) +a(n-2) -a(n-3) -a(n-4) for n>6

EXAMPLE

Some solutions for n=5

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

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

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

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

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

CROSSREFS

Cf. A317764.

Sequence in context: A096338 A198381 A309874 * A014279 A050543 A025588

Adjacent sequences:  A317756 A317757 A317758 * A317760 A317761 A317762

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 06 2018

STATUS

approved

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Last modified October 14 17:43 EDT 2019. Contains 328022 sequences. (Running on oeis4.)