A301902 Number of n X 3 0..1 arrays with every element equal to 0, 2 or 3 horizontally or antidiagonally adjacent elements, with upper left element zero.

1, 2, 3, 7, 16, 43, 117, 330, 935, 2667, 7616, 21775, 62273, 178130, 509563, 1457727, 4170224, 11930147, 34129757, 97638522, 279324735, 799093699, 2286051744, 6539949991, 18709526921, 53524323778, 153122698291, 438054310967

Offset

1,2

Links

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

Formula

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

Example

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

Crossrefs

Column 3 of A301906.

Sequence in context: A162092 A143884 A227546 * A332885 A122031 A246829

Adjacent sequences: A301899 A301900 A301901 * A301903 A301904 A301905

Keyword

nonn

Author

R. H. Hardin, Mar 28 2018

Status

approved