A206790 Number of nX1 0..3 arrays avoiding the pattern z z+1 z in any row, column, diagonal or antidiagonal

4, 16, 61, 232, 883, 3361, 12793, 48694, 185344, 705475, 2685250, 10220869, 38903701, 148079185, 563633908, 2145360148, 8165885869, 31081817236, 118306743223, 450311041525, 1714019240113, 6524072662150, 24832582450012

Offset

1,1

Comments

Column 1 of A206797

Links

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

Formula

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

Empirical: G.f.: -x*(4+x^2) / ( -1+4*x-x^2+x^3 ). - R. J. Mathar, Jul 17 2014

Example

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

Crossrefs

Sequence in context: A133161 A103820 A206570 * A283858 A283409 A192468

Adjacent sequences: A206787 A206788 A206789 * A206791 A206792 A206793

Keyword

nonn

Author

R. H. Hardin, Feb 12 2012

Status

approved