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A317891 Number of nX3 0..1 arrays with every element unequal to 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero. 1
0, 1, 4, 13, 59, 252, 1074, 4633, 19933, 85732, 368847, 1586817, 6826551, 29368380, 126345008, 543545426, 2338372742, 10059853024, 43278232785, 186186164251, 800986675100, 3445904026216, 14824534451888, 63776245668953 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Column 3 of A317896.

LINKS

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

FORMULA

Empirical: a(n) = 4*a(n-1) +8*a(n-3) -10*a(n-4) +3*a(n-5) -17*a(n-6) -7*a(n-7) -21*a(n-8) +6*a(n-9) +10*a(n-10) +4*a(n-11) -18*a(n-12) -21*a(n-13) -9*a(n-14) -a(n-15) +2*a(n-16) for n>18

EXAMPLE

Some solutions for n=5

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

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

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

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

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

CROSSREFS

Cf. A317896.

Sequence in context: A219572 A026663 A149486 * A115455 A241470 A219367

Adjacent sequences:  A317888 A317889 A317890 * A317892 A317893 A317894

KEYWORD

nonn

AUTHOR

R. H. Hardin, Aug 10 2018

STATUS

approved

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Last modified May 26 08:00 EDT 2022. Contains 354077 sequences. (Running on oeis4.)