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A303508
Number of nX3 0..1 arrays with every element equal to 0, 1, 2, 4, 5 or 6 horizontally, diagonally or antidiagonally adjacent elements, with upper left element zero.
1
4, 20, 78, 420, 2088, 9916, 49740, 245904, 1204720, 5966528, 29461128, 145208512, 717277504, 3540859200, 17473224048, 86264173904, 425824598480, 2101839903376, 10375467545712, 51215782794640, 252809675084016, 1247933698121232
OFFSET
1,1
COMMENTS
Column 3 of A303513.
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) +6*a(n-2) +36*a(n-3) -58*a(n-4) -116*a(n-5) -196*a(n-6) -160*a(n-7) -36*a(n-8) -240*a(n-9) -64*a(n-10) +232*a(n-11) +184*a(n-12) -64*a(n-14)
EXAMPLE
Some solutions for n=5
..0..0..0. .0..1..0. .0..1..0. .0..1..1. .0..1..0. .0..0..0. .0..1..0
..1..1..1. .0..0..1. .0..0..0. .0..1..0. .0..1..0. .1..0..1. .0..1..1
..0..0..0. .0..0..0. .0..0..1. .1..1..0. .0..0..0. .1..1..1. .0..0..1
..1..0..1. .0..1..0. .0..1..0. .0..0..1. .1..1..0. .1..0..0. .1..0..1
..0..0..0. .1..1..0. .0..1..0. .1..0..1. .1..1..0. .1..0..1. .1..0..1
CROSSREFS
Cf. A303513.
Sequence in context: A145563 A125669 A295116 * A258627 A082138 A074358
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 25 2018
STATUS
approved