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A228684 Number of 3 X n binary arrays with no two ones adjacent horizontally, diagonally or antidiagonally. 1
8, 17, 77, 216, 809, 2529, 8832, 28793, 97933, 324464, 1092561, 3642241, 12217528, 40825697, 136745357, 457357256, 1531058169, 5122533089, 17144628912, 57369165513, 191993439053, 642478726624, 2150072260001, 7195049684481 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = 2*a(n-1) + 6*a(n-2) - 5*a(n-3).

Empirical g.f.: x*(8 + x - 5*x^2) / (1 - 2*x - 6*x^2 + 5*x^3). - Colin Barker, Sep 12 2018

EXAMPLE

Some solutions for n=4:

..0..0..0..1....0..0..0..0....0..0..0..0....1..0..1..0....0..1..0..0

..1..0..0..0....1..0..1..0....0..1..0..0....1..0..0..0....0..0..0..0

..1..0..1..0....0..0..0..0....0..0..0..1....0..0..0..1....1..0..1..0

CROSSREFS

Row 3 of A228683.

Sequence in context: A186255 A244792 A187987 * A171065 A134790 A350683

Adjacent sequences:  A228681 A228682 A228683 * A228685 A228686 A228687

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 30 2013

STATUS

approved

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Last modified May 23 10:51 EDT 2022. Contains 353975 sequences. (Running on oeis4.)