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A317817
Number of nX2 0..1 arrays with every element unequal to 1, 2 or 3 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.
3
1, 5, 16, 50, 160, 511, 1634, 5226, 16716, 53471, 171045, 547149, 1750258, 5598852, 17910021, 57291907, 183269625, 586256561, 1875361283, 5999045795, 19190195958, 61387032829, 196369427849, 628161199864, 2009408986694, 6427847623748
OFFSET
1,2
COMMENTS
Column 2 of A317823.
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) +a(n-2) -3*a(n-4) -2*a(n-5) -a(n-6)
EXAMPLE
Some solutions for n=5
..0..1. .0..1. .0..0. .0..1. .0..1. .0..0. .0..1. .0..0. .0..1. .0..1
..0..1. .0..0. .1..1. .0..1. .1..1. .1..1. .0..1. .1..0. .1..0. .1..1
..1..1. .1..0. .0..0. .0..0. .0..0. .0..1. .0..0. .1..0. .1..0. .1..0
..0..0. .1..0. .1..1. .1..1. .1..1. .0..0. .0..1. .0..0. .1..0. .0..1
..1..0. .1..0. .0..0. .0..1. .0..1. .0..1. .1..0. .0..1. .1..1. .0..1
CROSSREFS
Cf. A317823.
Sequence in context: A037480 A027108 A304168 * A077840 A007343 A371437
KEYWORD
nonn
AUTHOR
R. H. Hardin, Aug 07 2018
STATUS
approved