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A268974
Number of 4Xn 0..2 arrays with some element plus some horizontally or antidiagonally adjacent neighbor totalling two not more than once.
1
81, 1728, 15552, 136080, 1125360, 9093528, 72081792, 563173128, 4349328912, 33272350344, 252534743280, 1904015932416, 14274182767248, 106487231224248, 791006745522096, 5853579437553624, 43172409083833728, 317460508504648992
OFFSET
1,1
COMMENTS
Row 4 of A268971.
LINKS
FORMULA
Empirical: a(n) = 18*a(n-1) -111*a(n-2) +282*a(n-3) -333*a(n-4) +180*a(n-5) -36*a(n-6) for n>12
EXAMPLE
Some solutions for n=4
..2..1..0..0. .0..0..1..2. .0..1..0..0. .2..1..0..0. .0..1..2..1
..0..0..1..2. .0..2..1..2. .0..0..0..0. .0..0..0..0. .2..1..0..0
..1..2..2..2. .1..0..1..0. .2..1..0..0. .1..0..1..1. .0..0..1..2
..2..1..0..0. .0..0..0..0. .2..1..0..1. .1..0..0..0. .1..0..0..0
CROSSREFS
Cf. A268971.
Sequence in context: A050634 A065791 A237503 * A206677 A237091 A253306
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 16 2016
STATUS
approved