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

Author

R. H. Hardin, Nov 14 2013

Keywords

• nonn

Examples

			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
		

Links

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

Crossrefs

Column 2 of A231839.

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