A251374 Number of (n+1) X (1+1) 0..3 arrays with every 2 X 2 subblock summing to 5 6 or 7.

124, 1048, 9124, 80296, 709396, 6276040, 55551652, 491795368, 4354105588, 38549885704, 341311285636, 3021895319272, 26755225413460, 236885220581704, 2097332909359972, 18569354042228776, 164409242545738420

Offset

1,1

Links

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

Formula

Empirical: a(n) = 10*a(n-1) - 3*a(n-2) - 66*a(n-3) + 24*a(n-4).

Empirical g.f.: 4*x*(31 - 48*x - 246*x^2 + 96*x^3) / (1 - 10*x + 3*x^2 + 66*x^3 - 24*x^4). - Colin Barker, Nov 29 2018

Example

Some solutions for n=4:
..2..1....0..3....3..0....1..2....2..2....0..3....0..2....1..1....1..1....3..1
..0..2....3..0....1..1....0..3....1..0....2..2....1..3....1..2....3..0....2..1
..1..3....2..1....1..3....2..0....1..3....1..2....0..2....1..3....2..1....3..1
..0..1....2..2....1..1....1..2....0..3....1..1....1..3....3..0....2..0....0..1
..3..2....1..0....0..3....2..1....2..1....3..0....3..0....1..3....1..2....3..2

Crossrefs

Column 1 of A251381.

Sequence in context: A206197 A206190 A251381 * A209730 A185860 A204634

Adjacent sequences: A251371 A251372 A251373 * A251375 A251376 A251377

Keyword

nonn

Author

R. H. Hardin, Dec 01 2014

Status

approved