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A317857 Number of nX2 0..1 arrays with every element unequal to 1, 2 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero. 3
1, 3, 6, 10, 21, 46, 102, 220, 491, 1077, 2393, 5271, 11682, 25799, 57090, 126209, 279123, 617274, 1364930, 3018713, 6675002, 14762294, 32643544, 72191407, 159639957, 353036505, 780698639, 1726457594, 3817890631, 8442936930 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A317863.

LINKS

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

FORMULA

Empirical: a(n) = a(n-1) +4*a(n-2) -2*a(n-3) -2*a(n-4) +a(n-5) -4*a(n-6) +4*a(n-7) -a(n-8)

EXAMPLE

Some solutions for n=5

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

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

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

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

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

CROSSREFS

Cf. A317863.

Sequence in context: A068709 A068804 A117834 * A220827 A063015 A282515

Adjacent sequences:  A317854 A317855 A317856 * A317858 A317859 A317860

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 09 2018

STATUS

approved

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Last modified May 9 07:36 EDT 2021. Contains 343692 sequences. (Running on oeis4.)