A209891 Number of (n+1)X3 0..2 arrays with every 2X2 subblock having two distinct values, and new values 0..2 introduced in row major order

34, 280, 2304, 19008, 156800, 1293568, 10671616, 88038400, 726296576, 5991780352, 49430814720, 407792893952, 3364197924864, 27753861939200, 228963000909824, 1888892288237568, 15582928518512640, 128555589286494208

Offset

1,1

Comments

Column 2 of A209897

Links

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

Formula

Empirical: a(n) = 8*a(n-1) +4*a(n-2) -16*a(n-3).

Empirical G.f.: 2*x*(17+4*x-36*x^2)/(1-8*x-4*x^2+16*x^3). [Colin Barker, Mar 15 2012]

Example

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

Crossrefs

Sequence in context: A301543 A252999 A229327 * A027006 A156531 A220565

Adjacent sequences: A209888 A209889 A209890 * A209892 A209893 A209894

Keyword

nonn

Author

R. H. Hardin Mar 14 2012

Status

approved