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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 (list; graph; refs; listen; history; text; internal format)
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 A275013

Adjacent sequences:  A188857 A188858 A188859 * A188861 A188862 A188863

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 12 2011

EXTENSIONS

a(0)=1 prepended by Alois P. Heinz, Mar 30 2017

STATUS

approved

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Last modified February 20 13:33 EST 2019. Contains 320327 sequences. (Running on oeis4.)