A230588 Number of n X 2 0..5 arrays x(i,j) with each element horizontally or vertically next to at least one element with value (x(i,j)+1) mod 6, and upper left element zero.

0, 0, 2, 8, 30, 120, 506, 2144, 9030, 37920, 159218, 668792, 2809710, 11804040, 49589354, 208325456, 875178390, 3676643760, 15445668962, 64887621608, 272594409150, 1145175432600, 4810908576986, 20210738740544, 84905783253990, 356691168912960, 1498467890613458

Offset

1,3

Links

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

Formula

Empirical: a(n) = 5*a(n-1) -5*a(n-2) +5*a(n-3) +8*a(n-4).

Empirical g.f.: 2*x^3*(-1+x) / ( -1+5*x-5*x^2+5*x^3+8*x^4 ). - R. J. Mathar, Oct 27 2013

Example

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

Crossrefs

Column 2 of A230592.

Sequence in context: A370539 A150759 A150760 * A151303 A150761 A373176

Adjacent sequences: A230585 A230586 A230587 * A230589 A230590 A230591

Keyword

nonn

Author

R. H. Hardin, Oct 24 2013

Status

approved