A219073 Hilltop maps: number of n X 3 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal, diagonal or antidiagonal neighbor in a random 0..1 n X 3 array.

5, 47, 337, 2469, 18499, 137251, 1019123, 7573641, 56263253, 417979331, 3105269893, 23069495037, 171386678155, 1273258576351, 9459233511263, 70274099126769, 522077106920261, 3878591175268919, 28814650755208777

Offset

1,1

Comments

Column 3 of A219078.

Links

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

Formula

Empirical: a(n) = 5*a(n-1) + 11*a(n-2) + 51*a(n-3) + 7*a(n-4) + 27*a(n-5) - 33*a(n-6) - 3*a(n-7).

Empirical g.f.: x*(5 + 22*x + 47*x^2 + 12*x^3 + 15*x^4 - 54*x^5 - 3*x^6) / (1 - 5*x - 11*x^2 - 51*x^3 - 7*x^4 - 27*x^5 + 33*x^6 + 3*x^7). - Colin Barker, Jul 25 2018

Example

Some solutions for n=3.
..0..1..1....1..0..1....1..0..1....0..1..1....1..1..1....1..0..0....1..1..0
..0..0..0....1..0..0....0..0..1....0..0..1....0..1..1....0..1..1....1..1..1
..0..1..0....1..1..1....0..1..1....0..1..1....0..1..0....0..1..1....0..1..1

Crossrefs

Cf. A219078.

Sequence in context: A304371 A049281 A354894 * A327595 A353545 A198854

Adjacent sequences: A219070 A219071 A219072 * A219074 A219075 A219076

Keyword

nonn

Author

R. H. Hardin, Nov 11 2012

Status

approved