A237938 Number of (n+1) X (1+1) 0..2 arrays with the maximum minus the minimum of every 2 X 2 subblock equal.

81, 437, 2417, 13893, 81245, 482409, 2893685, 17487137, 106223237, 647551889, 3957272037, 24224070993, 148455289413, 910505201009, 5587258627429, 34298159298769, 210595144024709, 1293294251436721, 7943185773864101

Offset

1,1

Links

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

Formula

Empirical: a(n) = 8*a(n-1) - a(n-2) - 64*a(n-3) - 14*a(n-4) + 88*a(n-5) + 8*a(n-6) - 24*a(n-7).

Empirical g.f.: x*(81 - 211*x - 998*x^2 + 178*x^3 + 1620*x^4 + 20*x^5 - 456*x^6) / ((1 - x)*(1 - 2*x - 8*x^2 - 4*x^3)*(1 - 5*x - 8*x^2 + 6*x^3)). - Colin Barker, Oct 24 2018

Example

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

Crossrefs

Column 1 of A237945.

Sequence in context: A237308 A237301 A237945 * A017630 A270538 A230064

Adjacent sequences: A237935 A237936 A237937 * A237939 A237940 A237941

Keyword

nonn

Author

R. H. Hardin, Feb 16 2014

Status

approved