A281600 Number of n X 3 0..2 arrays with no element equal to more than one of its horizontal, diagonal or antidiagonal neighbors and with new values introduced in order 0 sequentially upwards.

4, 29, 209, 1623, 12413, 95623, 736757, 5678559, 43771933, 337417047, 2601018757, 20050333455, 154561132461, 1191459205767, 9184555212821, 70800627012031, 545778076046781, 4207218532446903, 32432024283432101, 250007502993994607

Offset

1,1

Links

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

Formula

Empirical: a(n) = 7*a(n-1) + 10*a(n-2) - 26*a(n-3) - 64*a(n-4) - 40*a(n-5) for n>6.

Empirical g.f.: x*(4 + x - 34*x^2 - 26*x^3 - 28*x^4 - 48*x^5) / (1 - 7*x - 10*x^2 + 26*x^3 + 64*x^4 + 40*x^5). - Colin Barker, Feb 20 2019

Example

Some solutions for n=4:
..0..1..2. .0..1..2. .0..0..1. .0..1..0. .0..1..1. .0..1..2. .0..1..0
..2..1..0. .2..1..2. .2..1..2. .0..1..0. .0..2..0. .0..2..0. .0..1..0
..2..1..2. .2..0..0. .2..0..2. .0..1..2. .2..1..0. .0..2..0. .2..1..2
..0..0..1. .2..1..1. .2..0..2. .2..1..2. .2..0..2. .1..1..0. .0..0..1

Crossrefs

Column 3 of A281605.

Sequence in context: A288913 A100022 A001883 * A135429 A079756 A344098

Adjacent sequences: A281597 A281598 A281599 * A281601 A281602 A281603

Keyword

nonn

Author

R. H. Hardin, Jan 25 2017

Status

approved