A318039 Number of nX2 0..1 arrays with every element unequal to 0, 2, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

1, 2, 2, 3, 6, 17, 46, 124, 341, 947, 2630, 7299, 20261, 56255, 156198, 433692, 1204166, 3343438, 9283267, 25775570, 71567465, 198711506, 551734848, 1531926101, 4253488019, 11810073810, 32791403883, 91047370757, 252798683167

Offset

1,2

Comments

Column 2 of A318045.

Links

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

Formula

Empirical: a(n) = 3*a(n-1) -a(n-2) +a(n-3) +a(n-4) -2*a(n-5) -a(n-6) for n>7

Example

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

Crossrefs

Cf. A318045.

Sequence in context: A166678 A032908 A192366 * A060631 A275487 A096100

Adjacent sequences: A318036 A318037 A318038 * A318040 A318041 A318042

Keyword

nonn

Author

R. H. Hardin, Aug 13 2018

Status

approved