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A302618
Number of nX3 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
4, 17, 25, 71, 191, 498, 1321, 3505, 9240, 24460, 64759, 171268, 453200, 1199361, 3173346, 8396961, 22219739, 58794851, 155576745, 411673594, 1089327367, 2882467725, 7627305260, 20182608868, 53405199549, 141315536296, 373935069260
OFFSET
1,1
COMMENTS
Column 3 of A302623.
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) +a(n-2) +4*a(n-3) -4*a(n-4) -4*a(n-5) +a(n-6) -4*a(n-7) -4*a(n-9) for n>11
EXAMPLE
Some solutions for n=5
..0..1..0. .0..1..1. .0..1..0. .0..1..1. .0..1..0. .0..1..1. .0..0..1
..1..1..1. .0..1..0. .1..1..0. .1..0..0. .1..0..1. .0..0..1. .0..1..1
..0..0..0. .1..1..0. .0..0..1. .1..0..1. .1..0..1. .1..0..1. .0..1..0
..1..1..1. .1..0..0. .1..0..1. .1..0..0. .1..0..1. .1..0..1. .1..1..0
..0..0..0. .1..0..1. .1..0..1. .1..1..0. .1..0..1. .0..0..1. .1..0..0
CROSSREFS
Cf. A302623.
Sequence in context: A009226 A273022 A273119 * A171227 A061387 A366210
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 10 2018
STATUS
approved