A266007 Number of n X 3 integer arrays with each element equal to the number of horizontal and antidiagonal neighbors equal to itself.

2, 2, 6, 14, 22, 46, 102, 190, 374, 782, 1542, 3038, 6166, 12334, 24486, 49150, 98486, 196430, 393030, 786974, 1572694, 3144814, 6292710, 12583486, 25162742, 50333582, 100667526, 201318494, 402652822, 805322926, 1610596902, 3221208190

Offset

1,1

Links

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

Formula

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

Empirical g.f.: 2*x*(1 + 2*x^2) / ((1 - 2*x)*(1 + x + 2*x^2)). - Colin Barker, Jan 09 2019

Example

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

Crossrefs

Column 3 of A266012.

Sequence in context: A233230 A320070 A319866 * A051890 A071109 A005310

Adjacent sequences: A266004 A266005 A266006 * A266008 A266009 A266010

Keyword

nonn

Author

R. H. Hardin, Dec 20 2015

Status

approved