A318018 Number of nX2 0..1 arrays with every element unequal to 0, 1, 2 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

2, 6, 14, 35, 95, 257, 700, 1907, 5202, 14190, 38712, 105614, 288137, 786105, 2144674, 5851173, 15963362, 43551783, 118819435, 324167181, 884403808, 2412860224, 6582846451, 17959543175, 48997829987, 133677528403, 364703530888

Offset

1,1

Comments

Column 2 of A318024.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) +3*a(n-2) -2*a(n-3) -2*a(n-4) -a(n-6) +a(n-7)

Example

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

Crossrefs

Cf. A318024.

Sequence in context: A178320 A297187 A231509 * A025257 A283438 A362780

Adjacent sequences: A318015 A318016 A318017 * A318019 A318020 A318021

Keyword

nonn

Author

R. H. Hardin, Aug 12 2018

Status

approved