A198710 Number of n X 3 0..3 arrays with values 0..3 introduced in row major order and no element equal to any horizontal or vertical neighbor.

2, 25, 401, 6548, 107042, 1749965, 28609241, 467717288, 7646461682, 125007943505, 2043688517681, 33411178843628, 546221629207922, 8929887496964645, 145989990956749721, 2386712874803449568, 39019101990629849762

Offset

1,1

Comments

Column 3 of A198715.

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = 19*a(n-1) - 45*a(n-2) + 27*a(n-3).

Empirical g.f.: x*(2 - 13*x + 16*x^2) / ((1 - x)*(1 - 18*x + 27*x^2)). - Colin Barker, Mar 02 2018

Example

Some solutions with all values from 0 to 3 for n=4:
..0..1..2....0..1..2....0..1..0....0..1..2....0..1..0....0..1..2....0..1..0
..2..0..3....2..3..1....1..0..1....3..2..3....2..0..2....2..3..0....1..2..3
..0..1..0....0..1..2....0..2..3....2..3..0....0..3..1....0..2..1....3..0..1
..3..2..3....3..2..1....3..0..1....1..2..3....2..1..3....1..0..3....0..3..2

Crossrefs

Cf. A198715.

Sequence in context: A270346 A367506 A212022 * A074209 A209467 A121252

Adjacent sequences: A198707 A198708 A198709 * A198711 A198712 A198713

Keyword

nonn

Author

R. H. Hardin, Oct 29 2011

Status

approved