A239179 Number of (1+1) X (n+1) 0..2 arrays with no element greater than all horizontal neighbors or equal to all vertical neighbors.

6, 26, 98, 378, 1512, 6018, 23890, 94846, 376670, 1495888, 5940530, 23591238, 93686602, 372052590, 1477512180, 5867563418, 23301534646, 92536114306, 367483625614, 1459367686212, 5795507324598, 23015382256774, 91399732715398

Offset

1,1

Links

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

Formula

Empirical: a(n) = 4*a(n-1) - a(n-2) + 3*a(n-3) + 3*a(n-4) - 4*a(n-5) + a(n-6).

Empirical g.f.: 2*x*(3 + x - 3*x^3 + x^4) / (1 - 4*x + x^2 - 3*x^3 - 3*x^4 + 4*x^5 - x^6). - Colin Barker, Oct 25 2018

Example

Some solutions for n=5:
..1..1..0..1..1..1....1..1..1..0..1..1....1..1..1..1..1..0....0..0..1..2..2..1
..0..0..2..2..2..2....2..2..2..2..2..2....0..0..0..2..2..1....1..2..2..0..0..0

Crossrefs

Row 1 of A239178.

Sequence in context: A055589 A318947 A320816 * A307309 A186314 A234267

Adjacent sequences: A239176 A239177 A239178 * A239180 A239181 A239182

Keyword

nonn

Author

R. H. Hardin, Mar 11 2014

Status

approved