A269092 Number of n X 3 0..3 arrays with some element plus some horizontally or vertically adjacent neighbor totalling three exactly once.

24, 1152, 31296, 715320, 15024096, 300056400, 5795398368, 109294975080, 2024660774592, 36988673403168, 668280340085760, 11964667932759960, 212595089870143008, 3753382504394332656, 65903307050002080672

Offset

1,1

Links

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

Formula

Empirical: a(n) = 36*a(n-1) - 378*a(n-2) + 972*a(n-3) - 729*a(n-4) for n>5.

Empirical g.f.: 24*x*(1 + 12*x - 46*x^2 + 33*x^3 + 9*x^4) / (1 - 18*x + 27*x^2)^2. - Colin Barker, Jan 19 2019

Example

Some solutions for n=3:
..1..1..0. .2..0..0. .0..1..0. .2..0..1. .1..2..3. .1..1..0. .0..0..2
..3..3..1. .0..0..1. .0..0..2. .3..1..1. .3..3..3. .1..3..2. .0..0..2
..0..1..0. .2..2..1. .2..1..0. .1..3..2. .2..3..3. .2..2..3. .1..1..2

Crossrefs

Column 3 of A269097.

Sequence in context: A160260 A268149 A114051 * A010562 A080775 A191744

Adjacent sequences: A269089 A269090 A269091 * A269093 A269094 A269095

Keyword

nonn

Author

R. H. Hardin, Feb 19 2016

Status

approved