A163881 Number of nXnXn triangular binary arrays with all 1s connected, no 1 having more than 2 1s adjacent, and a path of 1s from peak vertex to anywhere on the bottom side

1, 3, 6, 20, 82, 430, 2890, 25268, 289456, 4331282

Offset

1,2

Links

Table of n, a(n) for n=1..10.

Example

All solutions for n=4
.....1........1........1........1........1........1........1........1...
....1.0......1.0......1.0......1.0......1.0......1.0......1.0......0.1..
...1.0.0....1.0.0....1.0.0....0.1.0....0.1.0....0.1.0....0.1.0....0.0.1.
..1.0.0.0..0.1.0.0..0.1.1.0..0.0.1.0..0.0.1.1..0.1.0.0..1.1.0.0..0.0.1.0
------
.....1........1........1........1........1........1........1........1...
....0.1......0.1......0.1......0.1......0.1......0.1......1.0......1.0..
...0.0.1....0.0.1....0.1.0....0.1.0....0.1.0....0.1.0....1.0.1....1.0.0.
..0.1.1.0..0.0.0.1..0.0.1.0..0.0.1.1..0.1.0.0..1.1.0.0..0.1.1.0..0.1.1.1
------
.....1........1........1........1...
....1.0......0.1......0.1......0.1..
...0.1.1....1.0.1....0.0.1....1.1.0.
..0.0.0.1..0.1.1.0..1.1.1.0..1.0.0.0

Crossrefs

Sequence in context: A334329 A162171 A194992 * A238474 A019017 A019049

Adjacent sequences: A163878 A163879 A163880 * A163882 A163883 A163884

Keyword

nonn

Author

R. H. Hardin Aug 06 2009

Status

approved