A251294 Number of (n+1) X (2+1) 0..3 arrays with every 2 X 2 subblock summing to 3 6 or 9.

444, 3140, 22536, 164480, 1221748, 9240612, 71163896, 557726448, 4443661924, 35942893556, 294664492808, 2444172105248, 20477585643732, 173008660351172, 1471862511047192, 12592888549938000, 108236211006760772

Offset

1,1

Links

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

Formula

Empirical: a(n) = 27*a(n-1) - 260*a(n-2) + 970*a(n-3) - 405*a(n-4) - 3449*a(n-5) - 722*a(n-6) + 840*a(n-7).

Empirical g.f.: 4*x*(111 - 2212*x + 13299*x^2 - 14568*x^3 - 56458*x^4 - 9662*x^5 + 13440*x^6) / ((1 - 6*x)*(1 - 7*x)*(1 - 6*x - 5*x^2)*(1 - 8*x - 7*x^2 + 4*x^3)). - Colin Barker, Nov 28 2018

Example

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

Crossrefs

Column 2 of A251300.

Sequence in context: A250075 A043507 A233711 * A233377 A098255 A028460

Adjacent sequences: A251291 A251292 A251293 * A251295 A251296 A251297

Keyword

nonn

Author

R. H. Hardin, Dec 01 2014

Status

approved