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Number of nondecreasing -n..n vectors of length 7 whose dot product with some nonincreasing -n..n vector equals 7
0

%I #3 Jun 06 2013 06:43:09

%S 2,92,1012,4280,15614,41428,109062,228130,457746,838870,1503000

%N Number of nondecreasing -n..n vectors of length 7 whose dot product with some nonincreasing -n..n vector equals 7

%C Row 7 of A226398

%e Some solutions for n=3

%e ..0....0...-3...-3...-3...-3...-3...-3...-1...-2...-3...-3...-3...-1...-3...-3

%e ..0....0....2...-2...-3...-2...-2...-1...-1...-1...-2...-3...-3....2...-3...-3

%e ..0....0....3...-2...-3...-2...-1...-1...-1....1...-2...-3...-2....2...-3...-2

%e ..1....2....3...-2...-2...-1....0...-1....0....2...-2...-2...-2....2...-3...-1

%e ..2....2....3...-1....0...-1....0....0....3....2...-2...-2...-1....2...-1....1

%e ..3....2....3....0....1....0....1....0....3....3...-1....1....3....3...-1....1

%e ..3....3....3....0....3....3....1....2....3....3....0....3....3....3....1....1

%K nonn

%O 1,1

%A _R. H. Hardin_ Jun 06 2013