A301946 Number of nX3 0..1 arrays with every element equal to 1, 2 or 3 horizontally or antidiagonally adjacent elements, with upper left element zero.

1, 5, 20, 83, 342, 1411, 5820, 24007, 99026, 408471, 1684896, 6950003, 28667966, 118252075, 487776260, 2012021183, 8299356842, 34233896031, 141210898600, 582478776747, 2402658213526, 9910689833651, 40880459994636, 168627213385143

Offset

1,2

Comments

Column 3 of A301951.

Links

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

Formula

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

Example

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

Crossrefs

Cf. A301951.

Sequence in context: A183933 A323262 A295601 * A292760 A270322 A056884

Adjacent sequences: A301943 A301944 A301945 * A301947 A301948 A301949

Keyword

nonn

Author

R. H. Hardin, Mar 29 2018

Status

approved