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A304128 Number of nX3 0..1 arrays with every element unequal to 0, 1, 3 or 6 king-move adjacent elements, with upper left element zero. 1
3, 7, 9, 19, 33, 53, 89, 155, 261, 439, 749, 1271, 2149, 3647, 6189, 10487, 17781, 30159, 51133, 86695, 147013, 249279, 422669, 716695, 1215253, 2060591, 3493981, 5924487, 10045669, 17033631, 28882605, 48973943, 83041205, 140806415, 238754301 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A304133.

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) +2*a(n-3) for n>7

EXAMPLE

Some solutions for n=5

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

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

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

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

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

CROSSREFS

Cf. A304133.

Sequence in context: A059621 A034926 A224849 * A304539 A306124 A096102

Adjacent sequences:  A304125 A304126 A304127 * A304129 A304130 A304131

KEYWORD

nonn

AUTHOR

R. H. Hardin, May 07 2018

STATUS

approved

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Last modified June 20 13:53 EDT 2021. Contains 345165 sequences. (Running on oeis4.)