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A305581 Number of nX3 0..1 arrays with every element unequal to 0, 1, 2, 7 or 8 king-move adjacent elements, with upper left element zero. 1
4, 3, 6, 8, 19, 33, 60, 112, 205, 377, 694, 1276, 2347, 4317, 7940, 14604, 26861, 49405, 90870, 167136, 307411, 565417, 1039964, 1912792, 3518173, 6470929, 11901894, 21890996, 40263819, 74056709, 136211524, 250532052, 460800285, 847543861 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 3 of A305586.

LINKS

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

Simon Plouffe Conjectures of the OEIS, as of June 20, 2018.

FORMULA

Empirical: a(n) = a(n-1) +a(n-2) +a(n-3) for n>5

Empirical: f(x)= -(2*x^4-5*x^3-x^2-x+4)*x/(x^3+x^2+x-1). - Simon Plouffe, Jun 20 2018

EXAMPLE

Some solutions for n=5

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

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

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

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

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

CROSSREFS

Cf. A305586.

Sequence in context: A211246 A197829 A187890 * A016702 A198610 A128754

Adjacent sequences:  A305578 A305579 A305580 * A305582 A305583 A305584

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jun 05 2018

STATUS

approved

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Last modified September 27 20:35 EDT 2020. Contains 337388 sequences. (Running on oeis4.)