A230470 Number of 2 X n 0..2 arrays x(i,j) with each element horizontally, diagonally or antidiagonally next to at least one element with value (x(i,j)+1) mod 3, and upper left element zero.

0, 0, 0, 36, 216, 1260, 6912, 38340, 213192, 1188252, 6624720, 36934452, 205906968, 1147892364, 6399246240, 35674383780, 198876914280, 1108695761532, 6180739391088, 34456287198996, 192086358160824, 1070839950246252

Offset

1,4

Links

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

Formula

Empirical: a(n) = 6*a(n-1) - a(n-2) - 12*a(n-3) + 20*a(n-4) + 24*a(n-5).

Empirical g.f.: 36*x^3 / ((1 + x)*(1 - 7*x + 8*x^2 + 4*x^3 - 24*x^4)). - Colin Barker, Sep 21 2018

Example

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

Crossrefs

Row 2 of A230469.

Sequence in context: A232677 A232670 A365308 * A066610 A176696 A269031

Adjacent sequences: A230467 A230468 A230469 * A230471 A230472 A230473

Keyword

nonn

Author

R. H. Hardin, Oct 20 2013

Status

approved