A236942 Number of (n+1) X (1+1) 0..3 arrays with the maximum of every 2 X 2 subblock equal.

256, 2796, 30698, 357316, 4195956, 50119046, 601976968, 7271574636, 88068458546, 1068829320076, 12986262880788, 157905941911406, 1920929508184336, 23375169249987756, 284496769631574458, 3462985011143368276

Offset

1,1

Links

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

Formula

Empirical: a(n) = 16*a(n-1) - 650*a(n-3) + 596*a(n-4) + 5184*a(n-5) - 1365*a(n-6) - 3780*a(n-7).

Empirical g.f.: 2*x*(128 - 650*x - 7019*x^2 + 16274*x^3 + 71862*x^4 - 28035*x^5 - 56700*x^6) / ((1 - x)*(1 - 3*x - 3*x^2)*(1 - 5*x - 20*x^2)*(1 - 7*x - 63*x^2)). - Colin Barker, Oct 21 2018

Example

Some solutions for n=3:
..1..3....0..3....3..1....3..0....0..1....1..2....3..0....0..3....0..0....2..3
..3..2....0..2....0..2....0..2....0..3....0..2....0..2....1..3....3..1....2..2
..3..2....3..0....3..3....3..2....2..3....1..0....0..3....1..3....2..0....3..3
..2..3....0..3....1..3....3..2....2..0....0..2....0..0....2..2....3..0....3..1

Crossrefs

Column 1 of A236949.

Sequence in context: A236127 A236124 A236949 * A236137 A236134 A236588

Adjacent sequences: A236939 A236940 A236941 * A236943 A236944 A236945

Keyword

nonn

Author

R. H. Hardin, Feb 01 2014

Status

approved