A303802 Number of n X 2 0..1 arrays with every element unequal to 0, 1, 3 or 4 king-move adjacent elements, with upper left element zero.

2, 5, 7, 17, 35, 61, 127, 265, 507, 1013, 2071, 4097, 8147, 16429, 32815, 65401, 131115, 262373, 523975, 1048433, 2097923, 4193821, 8387551, 16779241, 33554523, 67104725, 134221687, 268439777, 536858675, 1073745421, 2147504527, 4294939225

Offset

1,1

Comments

Column 2 of A303808.

Links

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

Formula

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

Example

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

Crossrefs

Cf. A303808.

Sequence in context: A318731 A256062 A303677 * A045357 A168035 A247323

Adjacent sequences: A303799 A303800 A303801 * A303803 A303804 A303805

Keyword

nonn

Author

R. H. Hardin, Apr 30 2018

Status

approved