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A318540
Number of nX3 0..1 arrays with every element unequal to 0, 1, 4 or 6 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.
1
3, 3, 6, 13, 26, 52, 107, 218, 442, 899, 1829, 3720, 7565, 15384, 31288, 63632, 129408, 263180, 535236, 1088521, 2213749, 4502149, 9156120, 18621004, 37869943, 77016935, 156631035, 318543977, 647829886, 1317505875, 2679440650, 5449237333
OFFSET
1,1
COMMENTS
Column 3 of A318545.
LINKS
FORMULA
Empirical: a(n) = a(n-1) +3*a(n-3) +a(n-4) +3*a(n-5) +a(n-7) for n>8
EXAMPLE
Some solutions for n=5
..0..0..0. .0..1..0. .0..0..0. .0..0..0. .0..1..0. .0..0..0. .0..0..0
..0..0..0. .0..0..0. .0..0..1. .0..0..0. .0..0..0. .1..0..0. .1..0..0
..0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..0..1. .0..0..1. .0..0..0
..0..0..1. .0..0..0. .0..0..0. .0..1..0. .0..0..0. .0..0..0. .0..0..1
..0..0..0. .0..1..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0. .0..0..0
CROSSREFS
Cf. A318545.
Sequence in context: A123140 A123289 A096572 * A325879 A325865 A110523
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 28 2018
STATUS
approved