A205355 Number of (n+1) X 3 0..2 arrays with every 2 X 2 subblock having the same number of equal diagonal or antidiagonal elements, and new values 0..2 introduced in row major order.

50, 275, 1562, 8948, 51458, 296774, 1716002, 9946442, 57787010, 336482834, 1963466114, 11480698658, 67259440130, 394759998530, 2320933378562, 13667740361858, 80610335471618, 476103197966594, 2815694162688002

Offset

1,1

Comments

Column 2 of A205361.

Links

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

Formula

Empirical: a(n) = 15*a(n-1) - 76*a(n-2) + 146*a(n-3) - 84*a(n-4).

Empirical g.f.: x*(50 - 475*x + 1237*x^2 - 882*x^3) / ((1 - x)*(1 - 6*x)*(1 - 8*x + 14*x^2)). - Colin Barker, Jun 11 2018

Example

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

Crossrefs

Cf. A205361.

Sequence in context: A091414 A186123 A220864 * A172519 A046656 A205620

Adjacent sequences: A205352 A205353 A205354 * A205356 A205357 A205358

Keyword

nonn

Author

R. H. Hardin, Jan 26 2012

Status

approved