A303882 Number of n X 2 0..1 arrays with every element unequal to 0, 2, 3 or 4 king-move adjacent elements, with upper left element zero.

1, 4, 8, 24, 82, 272, 908, 3076, 10444, 35480, 120648, 410432, 1396424, 4751472, 16168096, 55017104, 187214896, 637067040, 2167858112, 7376953152, 25102872672, 85422038784, 290680899264, 989152113472, 3365965684288, 11453976585344

Offset

1,2

Comments

Column 2 of A303888.

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) +2*a(n-3) -6*a(n-4) -4*a(n-5) for n>6.

Example

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

Crossrefs

Cf. A303888.

Sequence in context: A214201 A265185 A240530 * A008950 A045881 A303989

Adjacent sequences: A303879 A303880 A303881 * A303883 A303884 A303885

Keyword

nonn

Author

R. H. Hardin, May 02 2018

Status

approved