A163688 Number of n X 5 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, 13, 83, 389, 1561, 5808, 21608, 81280, 302869, 1103582, 3937976, 13827871, 47923048, 164209208, 557233266, 1875667336, 6269957318, 20829495789, 68804588538, 226093625926, 739449283873, 2408159168049, 7812647493736, 25257797249480, 81395524006138, 261529935822601

Offset

1,2

Links

Andrew Howroyd, Table of n, a(n) for n = 1..500

Example

All solutions for n=2:
...1.0.0.0.0...1.0.0.0.1...1.1.0.0.0...1.1.0.0.1...1.1.1.0.0...1.1.1.0.0
...1.1.1.1.1...1.1.1.1.1...0.1.1.1.1...0.1.1.1.1...0.0.1.1.1...1.0.1.1.1
------
...1.1.1.0.1...1.1.1.0.1...1.1.1.1.0...1.1.1.1.0...1.1.1.1.1...1.1.1.1.1
...0.0.1.1.1...1.0.1.1.1...0.0.0.1.1...1.0.0.1.1...0.0.0.0.1...1.0.0.0.1
------
...1.0.1.1.1
...1.1.1.0.1

Crossrefs

Row 5 of A391818.

Sequence in context: A142085 A396882 A376916 * A274398 A301953 A321589

Adjacent sequences: A163685 A163686 A163687 * A163689 A163690 A163691

Keyword

nonn

Author

R. H. Hardin, Aug 03 2009

Extensions

a(15) onward from Andrew Howroyd, Dec 21 2025

Status

approved