A269196 Number of n X 3 0..3 arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling three no more than once.

60, 1284, 25572, 471492, 8314020, 142233732, 2380537188, 39186271044, 636703584804, 10237337586180, 163189207436004, 2582623154662596, 40622651914004388, 635603382950474628, 9899530341266770020

Offset

1,1

Links

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

Formula

Empirical: a(n) = 30*a(n-1) -237*a(n-2) +180*a(n-3) -36*a(n-4) for n>5.

Empirical g.f.: 12*x*(1 - 6*x)*(5 - 13*x + 28*x^2 - 12*x^3) / (1 - 15*x + 6*x^2)^2. - Colin Barker, Jan 20 2019

Example

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

Crossrefs

Column 3 of A269201.

Sequence in context: A146347 A289156 A288960 * A054331 A160349 A281373

Adjacent sequences: A269193 A269194 A269195 * A269197 A269198 A269199

Keyword

nonn

Author

R. H. Hardin, Feb 20 2016

Status

approved