A317857 - OEIS

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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.

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

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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