A205620 Number of (n+1) X 3 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.

50, 306, 2052, 13800, 92934, 625512, 4211904, 28351440, 190894488, 1285019424, 8651903808, 58242716160, 392131883616, 2639804254848, 17772730684416, 119646649486080, 805521704829312, 5422860687684096, 36509097713452032

Offset

1,1

Comments

Column 2 of A205626.

Links

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

Formula

Empirical: a(n) = 40*a(n-2) + 40*a(n-3) - 28*a(n-4) for n>5.

Empirical g.f.: 2*x*(25 + 153*x + 26*x^2 - 220*x^3 + 7*x^4) / (1 - 40*x^2 - 40*x^3 + 28*x^4). - Colin Barker, Jun 12 2018

Example

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

Crossrefs

Cf. A205626.

Sequence in context: A205355 A172519 A046656 * A183698 A183690 A221572

Adjacent sequences: A205617 A205618 A205619 * A205621 A205622 A205623

Keyword

nonn

Author

R. H. Hardin, Jan 29 2012

Status

approved