A231833 Number of n X 2 0..3 arrays with no element less than a strict majority of its horizontal and antidiagonal neighbors.

4, 50, 422, 3823, 34350, 308419, 2771101, 24892609, 223618304, 2008825312, 18045827096, 162110668160, 1456284886944, 13082209530648, 117521102664489, 1055724534522884, 9483865176690522, 85196181144951446, 765340833781554407

Offset

1,1

Links

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

Formula

Empirical: a(n) = 4*a(n-1) + 34*a(n-2) + 86*a(n-3) + 91*a(n-4) + 46*a(n-5) + 11*a(n-6) + a(n-7).

Empirical g.f.: x*(2 + x)*(2 + 4*x + x^2)*(1 + 6*x + 5*x^2 + x^3) / (1 - 4*x - 34*x^2 - 86*x^3 - 91*x^4 - 46*x^5 - 11*x^6 - x^7). - Colin Barker, Oct 01 2018

Example

Some solutions for n=7:
..0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0....0..0
..2..2....2..2....0..0....0..0....0..0....2..0....0..2....0..0....0..0....2..0
..2..3....2..3....1..0....0..0....2..0....0..0....0..0....0..0....0..3....0..0
..3..3....2..2....0..0....1..3....0..2....3..1....3..2....0..1....0..0....0..0
..2..2....3..1....1..3....2..2....2..2....1..1....2..2....2..2....1..3....3..2
..1..0....1..1....2..2....2..1....3..2....3..3....3..1....3..3....0..0....2..2
..0..1....3..3....0..0....1..1....1..1....0..0....1..3....2..2....0..3....1..1

Crossrefs

Column 2 of A231839.

Sequence in context: A197473 A219566 A202790 * A028455 A232731 A215792

Adjacent sequences: A231830 A231831 A231832 * A231834 A231835 A231836

Keyword

nonn

Author

R. H. Hardin, Nov 14 2013

Status

approved