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A302064
Number of n X 3 0..1 arrays with every element equal to 0, 1, 2 or 4 horizontally or antidiagonally adjacent elements, with upper left element zero.
1
4, 25, 148, 884, 5296, 31760, 190528, 1143104, 6858496, 41150720, 246903808, 1481421824, 8888528896, 53331169280, 319987007488, 1919922028544, 11519532138496, 69117192765440, 414703156461568, 2488218938507264
OFFSET
1,1
COMMENTS
Column 3 of A302069.
LINKS
FORMULA
Empirical: a(n) = 8*a(n-1) - 12*a(n-2) for n>3.
EXAMPLE
Some solutions for n=5
..0..1..0. .0..1..1. .0..1..1. .0..0..1. .0..0..1. .0..0..1. .0..0..1
..0..1..1. .0..0..0. .0..0..1. .1..1..0. .1..0..1. .0..0..0. .0..1..0
..0..0..1. .1..0..0. .1..0..1. .0..1..1. .1..0..0. .1..0..1. .0..0..0
..1..1..0. .1..0..1. .0..1..0. .0..1..0. .1..1..0. .0..0..1. .0..1..1
..0..1..1. .0..1..0. .1..0..1. .1..1..1. .1..0..0. .0..1..1. .1..1..0
CROSSREFS
Cf. A302069.
Sequence in context: A173612 A349540 A072221 * A221849 A055846 A091634
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 31 2018
STATUS
approved