A235904 Number of (n+1) X (1+1) 0..2 arrays with the minimum plus the maximum unequal to the lower median plus the upper median in every 2 X 2 subblock.

48, 260, 1408, 7632, 41344, 224064, 1213952, 6578432, 35643392, 193143808, 1046528000, 5670785024, 30726979584, 166497435648, 902168182784, 4888469241856, 26488322654208, 143528684683264, 777716068515840

Offset

1,1

Links

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

Formula

Empirical: a(n) = 2*a(n-1) + 20*a(n-2) - 8*a(n-3).

Empirical g.f.: 4*x*(12 + 41*x - 18*x^2) / (1 - 2*x - 20*x^2 + 8*x^3). - Colin Barker, Oct 20 2018

Example

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

Crossrefs

Column 1 of A235911.

Sequence in context: A206047 A223434 A235911 * A275406 A205469 A115056

Adjacent sequences: A235901 A235902 A235903 * A235905 A235906 A235907

Keyword

nonn

Author

R. H. Hardin, Jan 16 2014

Status

approved