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A183425
Half the number of n X 2 0..2 arrays with no element equal its row sum plus its column sum mod 3.
1
3, 9, 32, 129, 513, 2048, 8193, 32769, 131072, 524289, 2097153, 8388608, 33554433, 134217729, 536870912, 2147483649, 8589934593, 34359738368, 137438953473, 549755813889, 2199023255552, 8796093022209, 35184372088833, 140737488355328
OFFSET
1,1
COMMENTS
Column 2 of A183429.
LINKS
FORMULA
Empirical: a(n)=4*a(n-1) + a(n-3) - 4*a(n-4).
Empirical g.f.: x*(3 - 3*x - 4*x^2 - 2*x^3) / ((1 - x)*(1 - 4*x)*(1 + x + x^2)). - Colin Barker, Mar 29 2018
EXAMPLE
Some solutions for 4 X 2:
..1..2....2..2....0..1....2..1....0..2....1..1....0..0....2..1....1..1....0..2
..0..2....2..2....0..1....1..2....0..0....1..2....0..1....0..1....1..2....1..0
..1..2....2..2....0..1....1..2....1..2....0..2....0..0....2..2....2..2....0..0
..1..1....2..2....0..1....2..1....1..0....1..2....1..0....2..1....2..1....1..2
CROSSREFS
Cf. A183429.
Sequence in context: A193621 A344623 A320180 * A039628 A194530 A324238
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 04 2011
STATUS
approved