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.

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

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