A318031 Number of nX2 0..1 arrays with every element unequal to 0, 1, 3 or 4 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

2, 3, 6, 11, 22, 46, 91, 182, 371, 746, 1498, 3027, 6102, 12283, 24766, 49926, 100587, 202726, 408611, 823442, 1659506, 3344611, 6740518, 13584427, 27377702, 55175838, 111198651, 224105366, 451652627, 910240506, 1834460106, 3697093427

Offset

1,1

Comments

Column 2 of A318037.

Links

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

Formula

Empirical: a(n) = a(n-1) +4*a(n-3) +a(n-5) -a(n-6)

Example

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

Crossrefs

Cf. A318037.

Sequence in context: A244521 A096202 A036653 * A316500 A123769 A093304

Adjacent sequences: A318028 A318029 A318030 * A318032 A318033 A318034

Keyword

nonn

Author

R. H. Hardin, Aug 13 2018

Status

approved