A305218 Number of nX3 0..1 arrays with every element unequal to 2, 3, 5, 6 or 7 king-move adjacent elements, with upper left element zero.

0, 4, 8, 15, 31, 92, 264, 784, 2378, 7342, 22596, 69617, 214983, 664217, 2052307, 6342935, 19606074, 60603932, 187335711, 579091828, 1790098137, 5533594957, 17105617402, 52877461311, 163456660240, 505283076436, 1561949355656

Offset

1,2

Comments

Column 3 of A305223.

Links

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

Formula

Empirical: a(n) = 2*a(n-1) +5*a(n-2) -12*a(n-4) -15*a(n-5) +3*a(n-6) +30*a(n-7) +14*a(n-8) -40*a(n-9) -44*a(n-10) +23*a(n-11) +66*a(n-12) +22*a(n-13) -15*a(n-14) -6*a(n-15) for n>18

Example

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

Crossrefs

Cf. A305223.

Sequence in context: A349201 A301203 A018921 * A321500 A103536 A011970

Adjacent sequences: A305215 A305216 A305217 * A305219 A305220 A305221

Keyword

nonn

Author

R. H. Hardin, May 27 2018

Status

approved