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A300968
Number of n X 3 0..1 arrays with every element equal to 1, 2, 3, 4 or 6 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.
1
1, 11, 72, 459, 2956, 18996, 122043, 784108, 5037730, 32366408, 207947716, 1336022660, 8583679582, 55148432350, 354317698174, 2276420668626, 14625549576730, 93966244187418, 603714410892078, 3878744894728494
OFFSET
1,2
COMMENTS
Column 3 of A300973.
LINKS
FORMULA
Empirical: a(n) = 7*a(n-1) -2*a(n-2) -11*a(n-3) -a(n-4) +10*a(n-5) +6*a(n-6) -4*a(n-7) -4*a(n-8) -2*a(n-9) for n>11.
EXAMPLE
Some solutions for n=5
..0..1..1. .0..1..1. .0..0..0. .0..1..1. .0..0..1. .0..0..0. .0..1..1
..0..1..1. .0..0..0. .0..1..1. .0..0..1. .0..1..1. .1..1..1. .0..1..1
..0..0..1. .0..0..0. .1..0..0. .0..1..0. .1..0..0. .0..0..0. .1..0..0
..0..1..0. .1..1..0. .0..1..0. .0..0..0. .0..1..0. .0..1..0. .0..0..1
..1..0..0. .1..0..0. .1..0..0. .1..1..1. .0..1..1. .0..1..0. .0..1..1
CROSSREFS
Cf. A300973.
Sequence in context: A006975 A260585 A084900 * A218619 A197308 A142015
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 17 2018
STATUS
approved