A251329 Number of (n+1) X (2+1) 0..2 arrays with every 2 X 2 subblock summing to 2 4 or 6.

171, 1115, 7393, 49937, 343299, 2399159, 17016861, 122275189, 888413951, 6515113419, 48143621385, 357960521241, 2674701190235, 20063864595135, 150970105831061, 1138711170122141, 8605011245388247, 65121221801574931

Offset

1,1

Links

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

Formula

Empirical: a(n) = 18*a(n-1) - 98*a(n-2) + 100*a(n-3) + 331*a(n-4) + 42*a(n-5) - 72*a(n-6).

Empirical g.f.: x*(171 - 1963*x + 4081*x^2 + 9033*x^3 + 846*x^4 - 1944*x^5) / ((1 + x)*(1 - 6*x)*(1 - 8*x + 3*x^2)*(1 - 5*x - 4*x^2)). - Colin Barker, Nov 29 2018

Example

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

Crossrefs

Column 2 of A251335.

Sequence in context: A158220 A079654 A220869 * A221754 A036518 A187133

Adjacent sequences: A251326 A251327 A251328 * A251330 A251331 A251332

Keyword

nonn

Author

R. H. Hardin, Dec 01 2014

Status

approved