A317817 Number of nX2 0..1 arrays with every element unequal to 1, 2 or 3 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

1, 5, 16, 50, 160, 511, 1634, 5226, 16716, 53471, 171045, 547149, 1750258, 5598852, 17910021, 57291907, 183269625, 586256561, 1875361283, 5999045795, 19190195958, 61387032829, 196369427849, 628161199864, 2009408986694, 6427847623748

Offset

1,2

Comments

Column 2 of A317823.

Links

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

Formula

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

Example

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

Crossrefs

Cf. A317823.

Sequence in context: A037480 A027108 A304168 * A077840 A007343 A371437

Adjacent sequences: A317814 A317815 A317816 * A317818 A317819 A317820

Keyword

nonn

Author

R. H. Hardin, Aug 07 2018

Status

approved