login
A239025
Number of n X 3 0..2 arrays with no element equal to the sum of elements to its left or one plus the sum of elements above it, modulo 3.
1
1, 4, 7, 28, 54, 212, 428, 1652, 3410, 13004, 27158, 102740, 215998, 812892, 1715842, 6435860, 13618366, 50970780, 108022954, 403751540, 856522206, 3198552316, 6789722794, 25340854612, 53813984430, 200773770908, 426474521338
OFFSET
1,2
LINKS
FORMULA
Empirical: a(n) = 17*a(n-2) - 96*a(n-4) + 210*a(n-6) - 152*a(n-8).
Empirical g.f.: x*(1 + 4*x - 10*x^2 - 40*x^3 + 31*x^4 + 120*x^5 - 28*x^6 - 104*x^7) / (1 - 17*x^2 + 96*x^4 - 210*x^6 + 152*x^8). - Colin Barker, Oct 25 2018
EXAMPLE
Some solutions for n=5:
..2..0..0....2..0..0....2..0..0....2..0..0....2..0..0....2..0..0....2..0..0
..1..0..0....1..0..2....1..0..0....1..2..2....1..0..0....2..0..0....2..0..0
..2..0..0....2..0..1....2..0..0....2..1..1....2..0..0....1..0..2....1..0..0
..1..2..2....1..2..2....1..2..2....2..0..0....2..0..0....2..0..1....2..0..0
..2..1..1....2..1..2....2..1..2....1..0..2....1..2..2....1..0..0....1..0..2
CROSSREFS
Column 3 of A239030.
Sequence in context: A146085 A359067 A061668 * A339393 A371456 A128386
KEYWORD
nonn
AUTHOR
R. H. Hardin, Mar 09 2014
STATUS
approved