A218314 Hilltop maps: number of n X 3 binary arrays indicating the locations of corresponding elements not exceeded by any king-move neighbor in a random 0..2 n X 3 array.

7, 63, 511, 4081, 32641, 261121, 2088919, 16710911, 133683711, 1069441121, 8555300481, 68440576001, 547509985575, 4379962908223, 35038767479807, 280302653750609, 2242361342901505, 17938411659180033, 143503460703541239

Offset

1,1

Comments

Column 3 of A218319.

Links

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

Formula

Empirical: a(n) = 7*a(n-1) + 7*a(n-2) + 7*a(n-3) + 7*a(n-4) + 7*a(n-5).

Empirical g.f.: 7*x*(1 + x + x^2)^2 / (1 - 7*x - 7*x^2 - 7*x^3 - 7*x^4 - 7*x^5). - Colin Barker, Jul 24 2018

Example

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

Crossrefs

Cf. A218319.

Sequence in context: A320073 A218191 A218367 * A218633 A218283 A218237

Adjacent sequences: A218311 A218312 A218313 * A218315 A218316 A218317

Keyword

nonn

Author

R. H. Hardin, Oct 25 2012

Status

approved