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A300641
Number of nX3 0..1 arrays with every element equal to 2, 3, 4 or 5 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.
1
0, 2, 2, 10, 30, 104, 340, 1144, 3795, 12683, 42227, 140876, 469517, 1565586, 5219130, 17400850, 58012053, 193409644, 644810491, 2149754855, 7167115016, 23894640479, 79662932803, 265590322328, 885458314722, 2952052210282, 9841922224851
OFFSET
1,2
COMMENTS
Column 3 of A300646.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) +4*a(n-2) -a(n-3) +7*a(n-4) +6*a(n-5) -2*a(n-6) -7*a(n-7) -11*a(n-8) -12*a(n-9) -8*a(n-10) -9*a(n-11) -3*a(n-12) -2*a(n-14) +a(n-15)
EXAMPLE
Some solutions for n=5
..0..0..0. .0..0..0. .0..0..1. .0..0..0. .0..0..0. .0..0..1. .0..0..1
..0..0..0. .0..0..0. .0..1..1. .0..0..0. .0..1..0. .0..1..1. .0..1..1
..1..1..1. .1..1..0. .0..0..0. .0..1..1. .1..1..0. .0..0..0. .1..1..1
..1..1..0. .1..0..0. .1..1..0. .0..1..0. .1..1..0. .0..0..1. .0..0..1
..1..0..0. .0..0..0. .1..0..0. .0..0..0. .1..0..0. .0..1..1. .0..1..1
CROSSREFS
Cf. A300646.
Sequence in context: A151364 A200949 A001885 * A078433 A059494 A052647
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 10 2018
STATUS
approved