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URL: https://oeis.org/A296984

⇱ A296984 - OEIS

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A296984
Number of n X 2 0..1 arrays with each 1 adjacent to 3, 4 or 5 king-move neighboring 1s.
1
1, 2, 4, 7, 14, 33, 77, 185, 460, 1148, 2881, 7264, 18335, 46325, 117117, 296154, 749008, 1894495, 4792002, 12121373, 30661425, 77559617, 196191748, 496279912, 1255373969, 3175556284, 8032794347, 20319525273, 51399691053, 130019197698
OFFSET
1,2
LINKS
FORMULA
Empirical: a(n) = 2*a(n-1) + a(n-2) + 3*a(n-3) - 4*a(n-4) - 2*a(n-5) - 4*a(n-6).
Empirical g.f.: x*(1 + x + 2*x^2)*(1 - x - 2*x^2 - 2*x^3) / (1 - 2*x - x^2 - 3*x^3 + 4*x^4 + 2*x^5 + 4*x^6). - Colin Barker, Feb 25 2019
EXAMPLE
Some solutions for n=7:
..1..1. .0..0. .1..1. .0..0. .1..1. .1..1. .1..1. .0..0. .0..0. .1..1
..1..1. .1..1. .1..1. .1..1. .1..1. .1..1. .1..1. .0..0. .1..1. .1..1
..1..0. .1..1. .1..1. .1..1. .0..0. .1..1. .0..0. .1..1. .1..1. .0..0
..1..1. .1..0. .1..1. .0..0. .0..0. .1..1. .1..1. .1..1. .1..0. .0..0
..1..1. .0..1. .0..1. .0..0. .0..0. .1..1. .1..1. .0..0. .1..0. .1..1
..1..1. .1..1. .1..1. .0..0. .0..0. .1..1. .0..0. .0..0. .1..1. .1..1
..1..1. .1..1. .1..1. .0..0. .0..0. .0..0. .0..0. .0..0. .1..1. .1..1
CROSSREFS
Column 2 of A296990.
Sequence in context: A325303 A356781 A113122 * A116584 A152477 A019998
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 22 2017
STATUS
approved