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A221196
Number of n X 3 arrays of occupancy after each element moves to some horizontal, diagonal or antidiagonal neighbor, with no occupancy greater than 2.
1
2, 10, 46, 212, 976, 4492, 20672, 95128, 437752, 2014400, 9269632, 42655888, 196288736, 903257824, 4156502752, 19126892096, 88015820416, 405020564416, 1863774679808, 8576493051520, 39466269101440, 181611106939904
OFFSET
1,1
COMMENTS
Column 3 of A221200.
LINKS
FORMULA
Empirical: a(n) = 6*a(n-1) - 6*a(n-2) - 2*a(n-3).
Empirical g.f.: 2*x*(1 - x - x^2) / (1 - 6*x + 6*x^2 + 2*x^3). - Colin Barker, Aug 04 2018
EXAMPLE
Some solutions for n=3:
..0..2..0....0..2..0....1..2..0....1..2..1....1..2..1....1..2..0....0..2..1
..1..2..2....0..2..2....0..2..1....1..2..0....0..2..1....1..2..0....0..2..2
..0..2..0....0..2..1....0..2..1....0..2..0....0..2..0....0..2..1....0..2..0
CROSSREFS
Cf. A221200.
Sequence in context: A290923 A106709 A204091 * A137193 A006213 A137635
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 04 2013
STATUS
approved