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A282310
Number of n X 2 0..1 arrays with no 1 equal to more than four of its king-move neighbors.
1
4, 16, 63, 249, 984, 3888, 15363, 60705, 239868, 947808, 3745143, 14798457, 58474224, 231053472, 912978459, 3607518465, 14254651188, 56325444336, 222562841967, 879428812473, 3474951296328, 13730828852304, 54255626883315
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) + 3*a(n-2) + 3*a(n-3).
Empirical g.f.: x*(4 + 4*x + 3*x^2) / (1 - 3*x - 3*x^2 - 3*x^3). - Colin Barker, Feb 20 2019
EXAMPLE
Some solutions for n=4:
..0..1. .0..1. .1..0. .1..1. .1..1. .1..0. .1..0. .0..0. .1..1. .1..0
..0..0. .1..0. .0..1. .1..1. .0..1. .1..0. .1..1. .1..1. .1..1. .1..1
..0..1. .0..1. .0..0. .1..0. .0..1. .0..0. .1..1. .0..0. .0..0. .0..1
..0..0. .0..1. .1..0. .1..0. .0..1. .1..0. .1..0. .0..0. .1..1. .0..1
CROSSREFS
Column 2 of A282316.
Sequence in context: A257838 A099503 A119376 * A022030 A135450 A265032
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 11 2017
STATUS
approved