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A283692
Number of 2 X n 0..1 arrays with no 1 equal to more than two of its horizontal, diagonal and antidiagonal neighbors.
1
4, 16, 49, 161, 548, 1824, 6081, 20353, 68036, 227376, 760145, 2541153, 8494692, 28397120, 94929633, 317342017, 1060849668, 3546339664, 11855139953, 39630819361, 132482782884, 442879752544, 1480512941569, 4949240890113
OFFSET
1,1
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) + a(n-2) + 3*a(n-3) - 6*a(n-4) - 8*a(n-5).
Empirical g.f.: x*(4 + 4*x - 3*x^2 - 14*x^3 - 8*x^4) / ((1 + x + 2*x^2)*(1 - 4*x + x^2 + 4*x^3)). - Colin Barker, Feb 21 2019
EXAMPLE
Some solutions for n=4:
..0..0..1..0. .1..0..0..1. .1..1..0..1. .0..0..0..0. .0..0..0..1
..0..0..0..0. .0..0..1..0. .0..1..0..1. .0..0..1..1. .0..1..0..1
CROSSREFS
Row 2 of A283691.
Sequence in context: A114185 A188516 A188501 * A173712 A085697 A262268
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 14 2017
STATUS
approved