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A297953 Number of n X 2 0..1 arrays with every element equal to 1, 2, 4 or 5 king-move adjacent elements, with upper left element zero. 8
1, 3, 7, 13, 23, 49, 99, 189, 383, 777, 1531, 3061, 6167, 12289, 24531, 49197, 98351, 196473, 393259, 786661, 1572551, 3145585, 6292227, 12582429, 25164767, 50333673, 100663387, 201322453, 402657143, 805310689, 1610600499, 3221229069 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 2 of A297959.

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.

Empirical g.f.: (1 + x)*(1 + 2*x^2 - 4*x^3) / ((1 - x)*(1 - 2*x)*(1 + x + 2*x^2)). - Colin Barker, Feb 19 2018

EXAMPLE

Some solutions for n=7:

..0..1. .0..0. .0..0. .0..0. .0..1. .0..1. .0..1. .0..1. .0..1. .0..0

..1..0. .0..1. .1..1. .1..1. .1..0. .0..1. .1..0. .1..0. .0..1. .1..1

..0..1. .1..1. .0..0. .0..0. .1..0. .1..0. .1..0. .1..0. .0..1. .0..0

..1..0. .1..1. .1..0. .1..1. .1..0. .1..0. .0..1. .1..0. .0..1. .1..1

..0..1. .1..1. .1..1. .0..0. .0..1. .0..1. .1..0. .1..0. .0..1. .0..1

..0..1. .1..0. .0..0. .1..1. .1..0. .0..1. .0..1. .0..1. .1..0. .0..0

..0..1. .0..0. .1..1. .0..0. .1..0. .0..1. .1..0. .1..0. .1..0. .1..1

CROSSREFS

Cf. A297959.

Sequence in context: A349793 A100720 A297852 * A084898 A147380 A146606

Adjacent sequences:  A297950 A297951 A297952 * A297954 A297955 A297956

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 09 2018

STATUS

approved

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Last modified May 27 16:48 EDT 2022. Contains 354110 sequences. (Running on oeis4.)