A237228 Number of (n+1) X (2+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.

268, 984, 3284, 10888, 36180, 120540, 401520, 1336540, 4448892, 14811704, 49313092, 164172108, 546554288, 1819586828, 6057775468, 20167512408, 67141506132, 223527096380, 744165226864, 2477470556540, 8247979825436

Offset

1,1

Links

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

Formula

Empirical: a(n) = a(n-1) + 4*a(n-2) + 5*a(n-3) + 21*a(n-4) + 12*a(n-5) + 4*a(n-6) for n>8.

Empirical g.f.: 4*x*(67 + 179*x + 307*x^2 + 582*x^3 + 402*x^4 + 127*x^5 - 6*x^6 - 8*x^7) / (1 - x - 4*x^2 - 5*x^3 - 21*x^4 - 12*x^5 - 4*x^6). - Colin Barker, Oct 21 2018

Example

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

Crossrefs

Column 2 of A237234.

Sequence in context: A234878 A194774 A279184 * A190352 A235175 A235169

Adjacent sequences: A237225 A237226 A237227 * A237229 A237230 A237231

Keyword

nonn

Author

R. H. Hardin, Feb 05 2014

Status

approved