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A318338
Number of nX3 0..1 arrays with every element unequal to 0, 1, 2 or 6 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.
1
4, 10, 20, 36, 76, 160, 344, 748, 1624, 3544, 7724, 16856, 36776, 80252, 175128, 382168, 833996, 1819992, 3971720, 8667356, 18914520, 41276600, 90076716, 196571800, 428972904, 936135100, 2042900376, 4458162072, 9728917388
OFFSET
1,1
COMMENTS
Column 3 of A318343.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) +2*a(n-2) -3*a(n-3) -2*a(n-4) +2*a(n-5) for n>6
EXAMPLE
Some solutions for n=5
..0..1..1. .0..0..1. .0..0..0. .0..1..1. .0..1..1. .0..0..0. .0..0..0
..1..1..1. .0..0..1. .0..0..0. .1..1..1. .1..1..1. .0..0..0. .0..0..0
..0..0..0. .0..0..1. .0..0..0. .1..1..1. .0..0..0. .1..1..1. .0..0..0
..0..0..1. .0..0..1. .1..1..1. .1..1..0. .0..0..0. .1..1..1. .1..1..1
..0..1..1. .0..0..1. .1..1..0. .1..0..0. .0..0..0. .1..1..1. .1..1..1
CROSSREFS
Cf. A318343.
Sequence in context: A369851 A275934 A369693 * A008058 A301170 A188280
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 24 2018
STATUS
approved