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A283094
Number of n X 2 0..1 arrays with no 1 equal to more than one of its horizontal and vertical neighbors, with the exception of exactly two elements.
2
0, 0, 6, 28, 142, 606, 2458, 9520, 35678, 130398, 467036, 1645468, 5718204, 19641544, 66795854, 225191264, 753433522, 2503868506, 8271225942, 27176203312, 88858110366, 289261952058, 937867756728, 3029675945528, 9754050602424
OFFSET
1,3
COMMENTS
Column 2 of A283100.
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) -3*a(n-2) -28*a(n-3) +6*a(n-4) +66*a(n-5) +33*a(n-6) -36*a(n-7) -30*a(n-8) +6*a(n-9) +9*a(n-10) -a(n-12).
Empirical: G.f.: -2*x^3*(-3+4*x+4*x^2-3*x^3+2*x^4-x^5-x^6+x^7)/(x^4-3*x^2-2*x+1)^3. - R. J. Mathar, Mar 02 2017
EXAMPLE
Some solutions for n=4:
..0..1. .0..0. .1..1. .0..0. .1..1. .1..0. .1..0. .0..1. .0..0. .0..0
..0..1. .1..0. .1..0. .0..1. .0..1. .1..1. .1..1. .1..1. .1..0. .0..1
..1..1. .1..0. .0..1. .0..1. .0..1. .0..1. .1..0. .1..0. .1..1. .1..1
..0..0. .1..1. .1..1. .1..1. .1..0. .1..0. .1..0. .0..1. .0..1. .1..0
CROSSREFS
Cf. A283100.
Sequence in context: A074247 A053783 A216383 * A110047 A163029 A309490
KEYWORD
nonn
AUTHOR
R. H. Hardin, Feb 28 2017
STATUS
approved