A218237 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..3 n X 3 array.

7, 63, 511, 4095, 32753, 262017, 2096129, 16769025, 134152151, 1073216767, 8585730559, 68685815807, 549486297185, 4395888543361, 35167093673985, 281336632008705, 2250692117004583, 18005529423519295, 144044175288040447

Offset

1,1

Comments

Column 3 of A218242.

Links

R. H. Hardin, Table of n, a(n) for n = 1..146

Formula

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

Empirical g.f.: 7*x*(1 + x)^2*(1 + x^2)^2 / (1 - 7*x - 7*x^2 - 7*x^3 - 7*x^4 - 7*x^5 - 7*x^6 - 7*x^7). - Colin Barker, Mar 10 2018

Example

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

Crossrefs

Cf. A218242.

Sequence in context: A218314 A218633 A218283 * A024088 A291034 A155132

Adjacent sequences: A218234 A218235 A218236 * A218238 A218239 A218240

Keyword

nonn

Author

R. H. Hardin, Oct 24 2012

Status

approved