A232331 Number of nX4 0..2 arrays with every 0 next to a 1 and every 1 next to a 2 horizontally or antidiagonally, with no adjacent elements equal

6, 32, 154, 734, 3472, 16338, 76630, 358656, 1676330, 7828014, 36533360, 170436130, 794923238, 3706958560, 17284778298, 80589690622, 375729468240, 1751693001458, 8166429157878, 38071572583616, 177486683779786, 827424427937102

Offset

1,1

Comments

Column 4 of A232335

Links

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

Formula

Empirical: a(n) = 7*a(n-1) -9*a(n-2) -8*a(n-3) -4*a(n-4).

Empirical: G.f.: -2*x*(-3+5*x+8*x^2+4*x^3) / ( 1-7*x+9*x^2+8*x^3+4*x^4 ). - R. J. Mathar, Nov 24 2013

Example

Some solutions for n=7
..0..1..2..1....2..1..2..1....0..1..0..2....2..1..2..1....2..1..0..2
..2..1..0..2....0..1..0..2....2..1..0..2....0..1..2..1....2..1..0..1
..2..1..0..2....0..1..0..1....0..2..1..0....0..1..2..1....2..1..2..1
..2..1..0..2....2..1..2..1....1..0..1..0....0..1..0..2....0..1..0..2
..0..1..0..2....0..1..0..2....1..2..1..2....0..2..0..2....0..2..1..2
..2..1..0..2....0..2..1..0....1..2..1..0....0..1..0..1....1..0..1..0
..0..2..1..0....1..2..1..0....1..0..2..1....2..1..2..1....2..0..2..1

Crossrefs

Sequence in context: A243026 A242542 A046725 * A231992 A292044 A006668

Adjacent sequences: A232328 A232329 A232330 * A232332 A232333 A232334

Keyword

nonn

Author

R. H. Hardin, Nov 22 2013

Status

approved