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A295979
Number of n X 2 0..1 arrays with each 1 adjacent to 2 or 3 king-move neighboring 1s.
1
1, 6, 15, 28, 90, 281, 737, 2095, 6268, 17965, 51360, 149540, 433577, 1250789, 3620541, 10489538, 30345263, 87801224, 254176114, 735652561, 2128923525, 6161699035, 17833776016, 51613806741, 149380609556, 432342904636
OFFSET
1,2
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) - 2*a(n-2) + 9*a(n-3) - 10*a(n-4) - 4*a(n-5) - 4*a(n-6).
Empirical g.f.: x*(1 + 3*x - x^2 - 14*x^3 - 8*x^4 - 4*x^5) / (1 - 3*x + 2*x^2 - 9*x^3 + 10*x^4 + 4*x^5 + 4*x^6). - Colin Barker, Feb 22 2019
EXAMPLE
Some solutions for n=7:
..1..1. .0..0. .0..0. .1..1. .0..0. .1..0. .0..0. .1..1. .0..0. .0..1
..1..0. .0..1. .0..1. .0..1. .0..1. .1..1. .0..0. .0..1. .0..0. .1..1
..0..1. .1..1. .1..1. .1..0. .1..1. .0..0. .1..0. .1..0. .1..1. .0..0
..1..1. .0..0. .0..1. .1..1. .0..1. .1..1. .1..1. .1..0. .0..1. .1..1
..0..0. .0..1. .1..0. .0..1. .0..0. .0..1. .0..0. .1..1. .1..0. .1..0
..1..0. .1..1. .1..0. .0..0. .1..1. .0..1. .1..1. .0..0. .1..0. .1..0
..1..1. .0..0. .1..1. .0..0. .0..1. .1..1. .0..1. .0..0. .1..1. .1..1
CROSSREFS
Column 2 of A295985.
Sequence in context: A144519 A066995 A263896 * A338488 A365418 A180953
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 01 2017
STATUS
approved