A237227 Number of (n+1) X (1+1) 0..2 arrays with the maximum plus the minimum of every 2 X 2 subblock differing from its horizontal and vertical neighbors by exactly one.

81, 268, 928, 2784, 9628, 28912, 100008, 300256, 1038560, 3118208, 10785696, 32383104, 112011072, 336303872, 1163253760, 3492571136, 12080581376, 36270926848, 125458829824, 376679553024, 1302910621696, 3911879237632

Offset

1,1

Links

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

Formula

Empirical: a(n) = 8*a(n-2) + 24*a(n-4) + 8*a(n-6) for n>7.

Empirical g.f.: x*(81 + 268*x + 280*x^2 + 640*x^3 + 260*x^4 + 208*x^5 + 64*x^6) / ((1 + 2*x^2)*(1 - 10*x^2 - 4*x^4)). - Colin Barker, Oct 21 2018

Example

Some solutions for n=5:
..2..1....1..2....0..2....1..0....0..2....2..1....2..0....1..0....2..1....2..1
..0..0....0..0....1..0....2..1....0..0....2..2....0..1....1..0....1..0....0..0
..1..0....1..0....0..1....1..1....1..0....0..1....0..0....2..1....1..1....1..0
..2..2....2..2....2..2....1..1....1..2....0..1....2..2....1..2....1..1....2..2
..1..1....1..2....1..1....2..2....1..1....1..2....1..2....0..1....0..0....1..2
..0..2....1..0....1..1....0..0....0..2....2..1....2..0....0..1....0..2....0..0

Crossrefs

Column 1 of A237234.

Sequence in context: A236746 A236739 A237234 * A206094 A202333 A207042

Adjacent sequences: A237224 A237225 A237226 * A237228 A237229 A237230

Keyword

nonn

Author

R. H. Hardin, Feb 05 2014

Status

approved