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A301603
Number of nX3 0..1 arrays with every element equal to 0, 2 or 3 horizontally or vertically adjacent elements, with upper left element zero.
1
1, 2, 2, 8, 13, 26, 55, 154, 356, 884, 2161, 5440, 13511, 33780, 84398, 211338, 528999, 1325014, 3319005, 8315948, 20836784, 52214530, 130847203, 327910100, 821772985, 2059471558, 5161348174, 12935209836, 32417941793, 81245379630, 203616360639
OFFSET
1,2
COMMENTS
Column 3 of A301608.
LINKS
FORMULA
Empirical: a(n) = a(n-1) +3*a(n-2) +4*a(n-3) +2*a(n-4) -8*a(n-5) -17*a(n-6) -19*a(n-7) -9*a(n-8) +6*a(n-9) +21*a(n-10) +15*a(n-11) +11*a(n-12) -2*a(n-13) -2*a(n-14) -4*a(n-15) -a(n-16) -a(n-17) +a(n-18)
EXAMPLE
Some solutions for n=5
..0..0..0. .0..0..1. .0..0..0. .0..1..1. .0..1..1. .0..0..0. .0..0..0
..0..0..0. .0..0..0. .0..1..0. .1..1..1. .1..1..1. .0..0..0. .0..1..0
..0..1..0. .0..1..0. .0..0..0. .1..0..1. .1..0..1. .0..1..0. .0..0..0
..0..0..0. .0..0..0. .0..1..0. .1..1..1. .1..1..1. .0..0..0. .1..1..1
..0..0..0. .0..0..0. .0..0..0. .0..1..1. .1..1..0. .1..0..0. .1..1..1
CROSSREFS
Cf. A301608.
Sequence in context: A006663 A094941 A002785 * A292038 A334600 A357787
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 24 2018
STATUS
approved