A163687 Number of nX4 binary arrays with all 1s connected, a path of 1s from upper left corner to lower right corner, and no 1 having more than two 1s adjacent

1, 8, 39, 132, 389, 1095, 3107, 8790, 24449, 66724, 179212, 475169, 1247181, 3249223, 8420475, 21735923, 55926076, 143501956, 367381497, 938864371, 2396062211, 6108616160, 15560958273

Offset

1,2

Links

Table of n, a(n) for n=1..23.

Example

All solutions for n=2
...1.0.0.0...1.0.0.1...1.1.0.0...1.1.0.1...1.1.1.0...1.1.1.0...1.1.1.1
...1.1.1.1...1.1.1.1...0.1.1.1...0.1.1.1...0.0.1.1...1.0.1.1...0.0.0.1
------
...1.1.1.1
...1.0.0.1

Crossrefs

Sequence in context: A245135 A200157 A101374 * A060446 A318267 A063002

Adjacent sequences: A163684 A163685 A163686 * A163688 A163689 A163690

Keyword

nonn

Author

R. H. Hardin Aug 03 2009

Status

approved