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A283635 Number of 2 X n 0..1 arrays with no 1 equal to more than one of its horizontal, diagonal and antidiagonal neighbors, with the exception of exactly two elements. 1
0, 0, 0, 36, 88, 516, 2076, 7372, 27108, 92436, 308980, 1013112, 3250572, 10288376, 32139960, 99287748, 303857760, 922134588, 2777950524, 8314125460, 24737931132, 73218906420, 215681560092, 632587894224, 1848037669164, 5379301732896 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

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

FORMULA

Empirical: a(n) = 3*a(n-1) + 6*a(n-2) - 5*a(n-3) - 42*a(n-4) - 33*a(n-5) + 51*a(n-6) + 156*a(n-7) + 144*a(n-8) + 64*a(n-9).

Empirical g.f.: 4*x^4*(9 - 5*x + 9*x^2 + 45*x^3) / (1 - x - 3*x^2 - 4*x^3)^3. - Colin Barker, Feb 21 2019

EXAMPLE

Some solutions for n=4:

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

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

CROSSREFS

Row 2 of A283634.

Sequence in context: A043963 A044174 A044555 * A305068 A182467 A060936

Adjacent sequences:  A283632 A283633 A283634 * A283636 A283637 A283638

KEYWORD

nonn

AUTHOR

R. H. Hardin, Mar 12 2017

STATUS

approved

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Last modified December 3 15:35 EST 2020. Contains 338906 sequences. (Running on oeis4.)