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A303722
Number of nX3 0..1 arrays with every element unequal to 0, 1, 2 or 3 king-move adjacent elements, with upper left element zero.
1
4, 21, 23, 46, 77, 151, 294, 549, 1051, 2032, 3877, 7421, 14262, 27333, 52371, 100472, 192665, 369353, 708294, 1358233, 2604287, 4993776, 9575821, 18361581, 35208486, 67513133, 129457227, 248235688, 475996017, 912729185, 1750170310, 3355977073
OFFSET
1,1
COMMENTS
Column 3 of A303727.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) +a(n-3) -2*a(n-4) -2*a(n-5) +2*a(n-6) for n>9
EXAMPLE
Some solutions for n=5
..0..1..0. .0..0..0. .0..1..1. .0..0..1. .0..1..1. .0..0..0. .0..1..1
..1..1..1. .1..1..1. .0..0..1. .0..0..0. .0..0..1. .0..0..0. .1..1..1
..1..1..1. .1..1..1. .0..0..0. .0..0..0. .0..0..0. .0..0..0. .1..1..1
..1..1..1. .0..1..1. .0..0..0. .0..0..0. .0..0..1. .1..0..0. .1..1..1
..1..1..1. .0..0..1. .1..1..1. .1..0..1. .0..1..1. .1..1..0. .0..1..0
CROSSREFS
Cf. A303727.
Sequence in context: A370979 A076943 A138228 * A305225 A272954 A133784
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 29 2018
STATUS
approved