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A302625
Number of 4Xn 0..1 arrays with every element equal to 0, 1, 2 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.
1
8, 81, 71, 130, 251, 497, 1051, 2274, 4999, 10972, 24236, 53509, 118285, 261369, 577860, 1277311, 2823836, 6242370, 13800217, 30507579, 67443317, 149095642, 329605433, 728654642, 1610832508, 3561051759, 7872390883, 17403425209
OFFSET
1,1
COMMENTS
Row 4 of A302623.
LINKS
FORMULA
Empirical: a(n) = a(n-1) +2*a(n-2) +2*a(n-3) +a(n-4) -4*a(n-5) -a(n-6) -2*a(n-7) +2*a(n-8) for n>11
EXAMPLE
Some solutions for n=5
..0..1..0..1..0. .0..0..1..0..0. .0..0..1..0..0. .0..1..0..0..1
..0..1..1..1..0. .1..0..1..0..1. .1..1..0..1..1. .0..1..0..1..1
..0..1..0..1..0. .1..0..1..0..1. .0..1..0..1..0. .1..1..0..1..0
..0..1..0..1..0. .1..0..1..0..0. .0..1..0..1..0. .1..0..0..1..0
CROSSREFS
Cf. A302623.
Sequence in context: A067449 A302974 A281472 * A078292 A210134 A274855
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 10 2018
STATUS
approved