A300345 Number of nX3 0..1 arrays with every element equal to 1 or 2 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

1, 6, 9, 26, 57, 133, 306, 709, 1642, 3805, 8811, 20409, 47276, 109514, 253686, 587661, 1361316, 3153496, 7305099, 16922333, 39200767, 90809027, 210360189, 487301922, 1128840861, 2614973750, 6057619008, 14032549467, 32506574899, 75301884294

Offset

1,2

Comments

Column 3 of A300350.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) +a(n-2) -2*a(n-5) -2*a(n-6) -2*a(n-7) -a(n-8) for n>10

Example

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

Crossrefs

Cf. A300350.

Sequence in context: A260565 A115644 A243708 * A024878 A007414 A274977

Adjacent sequences: A300342 A300343 A300344 * A300346 A300347 A300348

Keyword

nonn

Author

R. H. Hardin, Mar 03 2018

Status

approved