A318338 Number of nX3 0..1 arrays with every element unequal to 0, 1, 2 or 6 horizontally, vertically or antidiagonally adjacent elements, with upper left element zero.

4, 10, 20, 36, 76, 160, 344, 748, 1624, 3544, 7724, 16856, 36776, 80252, 175128, 382168, 833996, 1819992, 3971720, 8667356, 18914520, 41276600, 90076716, 196571800, 428972904, 936135100, 2042900376, 4458162072, 9728917388

Offset

1,1

Comments

Column 3 of A318343.

Links

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

Formula

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

Example

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

Crossrefs

Cf. A318343.

Sequence in context: A369851 A275934 A369693 * A008058 A301170 A188280

Adjacent sequences: A318335 A318336 A318337 * A318339 A318340 A318341

Keyword

nonn

Author

R. H. Hardin, Aug 24 2018

Status

approved