A304004 Number of n X 2 0..1 arrays with every element unequal to 0, 2, 3 or 5 king-move adjacent elements, with upper left element zero.

1, 4, 7, 13, 26, 49, 99, 194, 387, 773, 1538, 3081, 6147, 12298, 24587, 49157, 98330, 196609, 393251, 786450, 1572883, 3145797, 6291442, 12583033, 25165827, 50331738, 100663451, 201326533, 402653578, 805306225, 1610613155, 3221225698

Offset

1,2

Comments

Column 2 of A304010.

Links

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

Formula

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

Example

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

Crossrefs

Cf. A304010.

Sequence in context: A074864 A074865 A072683 * A293342 A298346 A122552

Adjacent sequences: A304001 A304002 A304003 * A304005 A304006 A304007

Keyword

nonn

Author

R. H. Hardin, May 04 2018

Status

approved