A318010 Number of nX2 0..1 arrays with every element unequal to 0, 1, 2 or 3 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

2, 8, 28, 97, 338, 1178, 4105, 14305, 49850, 173717, 605368, 2109583, 7351463, 25618337, 89274637, 311103754, 1084132616, 3777979256, 13165480909, 45878993986, 159878860766, 557144956745, 1941535618525, 6765852427390

Offset

1,1

Comments

Column 2 of A318016.

Links

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

Formula

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

Example

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

Crossrefs

Cf. A318016.

Sequence in context: A280279 A060995 A106731 * A291383 A277653 A066796

Adjacent sequences: A318007 A318008 A318009 * A318011 A318012 A318013

Keyword

nonn

Author

R. H. Hardin, Aug 12 2018

Status

approved