A203790 Number of (n+1) X 3 0..3 arrays with every 2 X 2 subblock having equal diagonal elements or equal antidiagonal elements.

784, 10576, 142192, 1911952, 25708528, 345682576, 4648124656, 62499715984, 840385055728, 11300004020368, 151942362599152, 2043050737911184, 27471313768440304, 369385383417191056, 4966837867034125552

Offset

1,1

Comments

Column 2 of A203796.

Links

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

Formula

Empirical: a(n) = 13*a(n-1) +6*a(n-2).

Empirical g.f.: 16*x*(49 + 24*x) / (1 - 13*x - 6*x^2). - Colin Barker, Jun 05 2018

Example

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

Crossrefs

Cf. A203796.

Sequence in context: A258539 A250809 A255145 * A223493 A231976 A188782

Adjacent sequences: A203787 A203788 A203789 * A203791 A203792 A203793

Keyword

nonn

Author

R. H. Hardin, Jan 05 2012

Status

approved