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A297817
Number of nX2 0..1 arrays with every element equal to 1, 2 or 3 king-move adjacent elements, with upper left element zero.
5
1, 4, 17, 49, 166, 573, 1933, 6538, 22165, 75089, 254350, 861661, 2919029, 9888610, 33499125, 113483321, 384441606, 1302353053, 4411914717, 14946017274, 50631856149, 171522942625, 581059476926, 1968425392285, 6668333757637
OFFSET
1,2
COMMENTS
Column 2 of A297823.
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) +a(n-2) +2*a(n-3) -2*a(n-4) -4*a(n-5) for n>6
EXAMPLE
Some solutions for n=7
..0..1. .0..0. .0..1. .0..0. .0..1. .0..1. .0..0. .0..0. .0..1. .0..1
..1..0. .1..1. .0..1. .1..1. .1..0. .0..1. .1..0. .1..0. .1..0. .0..1
..1..0. .0..0. .0..1. .1..0. .1..1. .0..0. .0..1. .1..0. .0..0. .1..0
..1..1. .0..0. .0..1. .0..0. .0..0. .0..1. .0..0. .0..0. .0..1. .0..1
..1..0. .1..1. .0..1. .1..0. .1..0. .0..1. .1..0. .1..0. .1..0. .0..1
..0..1. .0..1. .0..1. .1..0. .1..0. .0..1. .1..0. .0..1. .0..0. .1..0
..1..0. .0..1. .0..1. .1..0. .0..1. .0..1. .0..1. .0..1. .1..1. .1..0
CROSSREFS
Cf. A297823.
Sequence in context: A273334 A273766 A173704 * A184445 A334694 A228960
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 06 2018
STATUS
approved