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A269203
Number of 3Xn 0..3 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling three no more than once.
1
64, 1740, 25572, 400428, 5877228, 84310620, 1184381844, 16385570076, 223935582828, 3030348558252, 40673437553748, 542180347359564, 7185077761974828, 94737850175764476, 1243661129422894356
OFFSET
1,1
COMMENTS
Row 3 of A269201.
LINKS
FORMULA
Empirical: a(n) = 24*a(n-1) -130*a(n-2) -248*a(n-3) +935*a(n-4) +272*a(n-5) -1768*a(n-6) +960*a(n-7) -144*a(n-8)
EXAMPLE
Some solutions for n=3
..1..3..3. .1..3..1. .1..2..0. .0..0..0. .2..0..3. .1..1..1. .3..3..3
..3..1..1. .2..3..2. .3..1..0. .0..1..1. .1..3..1. .3..1..3. .3..3..3
..1..1..3. .2..3..1. .3..2..0. .3..3..3. .2..0..1. .1..2..0. .2..3..1
CROSSREFS
Cf. A269201.
Sequence in context: A269660 A234240 A017115 * A005609 A065788 A264275
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 20 2016
STATUS
approved