A230726 Number of n X 4 0..5 arrays x(i,j) with each element horizontally or antidiagonally next to at least one element with value (x(i,j)+1) mod 6, and upper left element zero.

0, 2, 30, 396, 6212, 95412, 1459082, 22379112, 343179162, 5262047702, 80687972676, 1237264461260, 18972099054156, 290916616713522, 4460891769710192, 68402949461361234, 1048885241311782830, 16083520658051806236

Offset

1,2

Links

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

Formula

Empirical: a(n) = 16*a(n-1) - 12*a(n-2) + 87*a(n-3) - 918*a(n-4) + 61*a(n-5) - a(n-6).

Empirical g.f.: 2*x^2*(1 - x)*(1 - 30*x^2 + x^3) / (1 - 16*x + 12*x^2 - 87*x^3 + 918*x^4 - 61*x^5 + x^6). - Colin Barker, Sep 22 2018

Example

Some solutions for n=4:
..0..1..0..5....0..1..2..3....0..1..2..1....0..1..2..3....0..1..2..3
..2..3..4..5....0..1..4..3....0..3..2..3....2..3..4..5....2..3..4..5
..2..1..0..5....0..5..4..3....4..5..4..3....2..1..0..3....2..5..0..1
..0..3..4..3....2..3..2..1....0..1..2..1....4..5..4..3....4..3..2..1

Crossrefs

Column 4 of A230730.

Sequence in context: A231597 A216119 A083446 * A091345 A147682 A211906

Adjacent sequences: A230723 A230724 A230725 * A230727 A230728 A230729

Keyword

nonn

Author

R. H. Hardin, Oct 28 2013

Status

approved