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A188860
Number of n X n binary arrays without the pattern 0 1 diagonally, vertically or antidiagonally.
2
1, 2, 7, 26, 95, 340, 1193, 4116, 14001, 47064, 156629, 516844, 1693073, 5511218, 17841247, 57477542, 184377699, 589195584, 1876395357, 5957318820, 18861068265, 59563612974, 187668462027, 590039959434, 1851508693479, 5799494052414, 18135645594003
OFFSET
0,2
COMMENTS
Diagonal of A188866.
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..2000 (terms n = 1..32 from R. H. Hardin)
FORMULA
G.f.: (3*x^2-3*x+1-x*sqrt(1-3*x^2-2*x))/(1-3*x)^2. - Alois P. Heinz, Mar 30 2017
EXAMPLE
Some solutions for 3X3
..1..1..1....0..0..0....1..1..1....1..1..1....1..1..0....1..1..1....1..1..1
..1..1..1....0..0..0....1..1..1....1..0..0....0..0..0....1..1..1....1..1..1
..1..1..0....0..0..0....1..0..0....0..0..0....0..0..0....1..0..1....0..0..0
MAPLE
a:= proc(n) option remember; `if`(n<3, (2*n-1)*n+1,
((10*n^2-49*n+33)*a(n-1)-(6*n^2-9*n-33)*a(n-2)
-(9*(n-3))*(2*n-7)*a(n-3))/((n-1)*(2*n-9)))
end:
seq(a(n), n=0..35); # Alois P. Heinz, Mar 30 2017
CROSSREFS
Cf. A188866.
Sequence in context: A134063 A087448 A289449 * A129273 A055988 A379627
KEYWORD
nonn
AUTHOR
R. H. Hardin, Apr 12 2011
EXTENSIONS
a(0)=1 prepended by Alois P. Heinz, Mar 30 2017
STATUS
approved