A205627 Number of 3 X (n+1) 0..2 arrays with every 2 X 2 subblock in a row having an equal number of equal diagonal or equal antidiagonal elements, adjacent rows differing in this number, and new values 0..2 introduced in row major order.

72, 306, 1512, 8004, 43248, 235464, 1284960, 7018128, 38341824, 209492256, 1144664448, 6254518848, 34175238912, 186736804992, 1020348532224, 5575287376128, 30463935384576, 166458035802624, 909543616813056

Offset

1,1

Comments

Row 2 of A205626.

Links

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

Formula

Empirical: a(n) = 6*a(n-1) +2*a(n-2) -28*a(n-3) +32*a(n-5).

Empirical g.f.: 6*x*(12 - 21*x - 78*x^2 + 56*x^3 + 128*x^4) / ((1 - 2*x)*(1 - 2*x^2)*(1 - 4*x - 8*x^2)). - Colin Barker, Jun 12 2018

Example

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

Crossrefs

Cf. A205626.

Sequence in context: A242534 A277430 A277991 * A234217 A234210 A157909

Adjacent sequences: A205624 A205625 A205626 * A205628 A205629 A205630

Keyword

nonn

Author

R. H. Hardin, Jan 29 2012

Status

approved