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A185562
1/4 the number of n X 4 0..3 arrays with no element equal both to the element above and to the element to its left.
1
64, 13500, 2842560, 598507920, 126017211780, 26533211918040, 5586628402633500, 1176277376648694960, 247667889663690066720, 52147040135402715629580, 10979678466093753927519840, 2311796391622216326875508300
OFFSET
1,1
COMMENTS
Column 4 of A185567.
LINKS
FORMULA
Empirical: a(n) = 217*a(n-1) - 1371*a(n-2) + 2835*a(n-3) - 2025*a(n-4).
Empirical g.f.: 4*x*(16 - 97*x + 201*x^2 - 135*x^3) / (1 - 217*x + 1371*x^2 - 2835*x^3 + 2025*x^4). - Colin Barker, Apr 16 2018
EXAMPLE
Some solutions for 3 X 4 with a(1,1)=0:
..0..0..2..0....0..0..3..0....0..2..0..2....0..0..3..1....0..2..2..0
..0..2..0..3....2..0..3..2....0..2..0..2....2..2..2..2....0..2..0..2
..0..3..3..2....2..2..1..2....2..3..2..1....0..3..0..0....0..2..3..2
CROSSREFS
Cf. A185567.
Sequence in context: A220300 A316485 A292025 * A264127 A135788 A016794
KEYWORD
nonn
AUTHOR
R. H. Hardin, Jan 31 2011
STATUS
approved