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A280400
Number of 2Xn 0..2 arrays with no element unequal to a strict majority of its horizontal and antidiagonal neighbors, with the exception of exactly one element, and with new values introduced in order 0 sequentially upwards.
1
0, 2, 6, 16, 34, 76, 158, 336, 698, 1460, 3030, 6296, 13042, 27004, 55822, 115296, 237866, 490308, 1009734, 2077736, 4271970, 8776972, 18019966, 36972016, 75808154, 155344596, 318145718, 651204536, 1332235218, 2724122780, 5567550190
OFFSET
1,2
COMMENTS
Row 2 of A280398.
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) +a(n-2) -7*a(n-3) +4*a(n-5).
Empirical g.f.: 2*x^2*(-1+2*x^2+3*x^3) / ( (x-1)*(1+x)^2*(2*x-1)^2 ). - R. J. Mathar, Jan 04 2017
Empirical: a(n) = 2^(n-1)*n/9 +2^(n-1)*47/27 +(-1)^n*2*n/9 -10*(-1)^n/27-2. - R. J. Mathar, Jan 04 2017
EXAMPLE
Some solutions for n=4
..0..0..0..0. .0..1..1..1. .0..0..1..0. .0..0..1..1. .0..0..0..0
..0..0..1..1. .1..1..1..1. .0..0..0..0. .0..1..1..2. .0..1..0..0
CROSSREFS
Cf. A280398.
Sequence in context: A235792 A192706 A248832 * A199477 A330884 A060354
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 02 2017
STATUS
approved