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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
OFFSET
1,1
COMMENTS
Column 3 of A304133.
LINKS
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
KEYWORD
nonn
AUTHOR
R. H. Hardin, May 07 2018
STATUS
approved