A301657 Number of nX3 0..1 arrays with every element equal to 0, 1 or 4 horizontally or vertically adjacent elements, with upper left element zero.

3, 4, 6, 9, 15, 26, 46, 83, 151, 276, 506, 929, 1707, 3138, 5770, 10611, 19515, 35892, 66014, 121417, 223319, 410746, 755478, 1389539, 2555759, 4700772, 8646066, 15902593, 29249427, 53798082, 98950098, 181997603, 334745779, 615693476

Offset

1,1

Comments

Column 3 of A301662.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) -a(n-4)

Example

Some solutions for n=5
..0..0..1. .0..1..0. .0..1..0. .0..1..0. .0..1..0. .0..1..0. .0..1..1
..1..1..0. .1..1..1. .0..1..0. .1..0..1. .1..1..1. .1..0..1. .1..0..0
..0..0..1. .0..1..0. .1..0..1. .1..0..1. .0..1..0. .0..0..0. .0..1..1
..1..1..0. .1..0..1. .1..0..1. .0..1..0. .1..0..1. .1..0..1. .1..0..0
..0..0..1. .0..1..0. .0..1..0. .0..1..0. .1..0..1. .0..1..0. .0..1..1

Crossrefs

Cf. A301662.

Sequence in context: A291866 A332829 A173270 * A241342 A018830 A102934

Adjacent sequences: A301654 A301655 A301656 * A301658 A301659 A301660

Keyword

nonn

Author

R. H. Hardin, Mar 25 2018

Status

approved