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A225307 Number of nX6 -1,1 arrays such that the sum over i=1..n,j=1..6 of i*x(i,j) is zero and rows are nondecreasing (ways to put 6 thrusters pointing east or west at each of n positions 1..n distance from the hinge of a south-pointing gate without turning the gate) 1
1, 3, 17, 83, 427, 2341, 13333, 77721, 461973, 2791167, 17087937, 105766229, 660771733, 4161393187, 26390549923, 168386196159, 1080202503299, 6962854947491, 45075011876699, 292931328936351, 1910374828122659 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Column 6 of A225310
LINKS
EXAMPLE
Some solutions for n=4
.-1.-1.-1.-1..1..1...-1.-1.-1.-1..1..1....1..1..1..1..1..1...-1.-1.-1..1..1..1
..1..1..1..1..1..1...-1.-1.-1.-1.-1..1...-1.-1.-1.-1.-1.-1...-1..1..1..1..1..1
.-1.-1..1..1..1..1...-1.-1.-1.-1..1..1...-1.-1.-1.-1.-1.-1...-1.-1.-1..1..1..1
.-1.-1.-1.-1.-1..1...-1..1..1..1..1..1....1..1..1..1..1..1...-1.-1.-1.-1..1..1
CROSSREFS
Sequence in context: A194596 A217623 A083217 * A318769 A344228 A216681
KEYWORD
nonn
AUTHOR
R. H. Hardin May 05 2013
STATUS
approved

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Last modified February 24 17:27 EST 2024. Contains 370307 sequences. (Running on oeis4.)