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Number of -n..n arrays x(0..6) of 7 elements with zero sum, adjacent elements differing by more than one, and elements alternately increasing and decreasing
1

%I #5 Mar 31 2012 12:36:38

%S 0,104,1534,9856,40632,127800,334278,765598,1585416,3034396,5450616,

%T 9293800,15170448,23863548,36362438,53897896,77976766,110422568,

%U 153414642,209534448,281809258,373763982,489469484,633600106,811486280

%N Number of -n..n arrays x(0..6) of 7 elements with zero sum, adjacent elements differing by more than one, and elements alternately increasing and decreasing

%C Row 7 of A200192

%H R. H. Hardin, <a href="/A200196/b200196.txt">Table of n, a(n) for n = 1..200</a>

%F Empirical: a(n) = 2*a(n-1) -a(n-3) -a(n-5) +a(n-6) -2*a(n-7) +2*a(n-8) +a(n-9) -a(n-13) -2*a(n-14) +2*a(n-15) -a(n-16) +a(n-17) +a(n-19) -2*a(n-21) +a(n-22)

%e Some solutions for n=5

%e .-3....1...-2....0...-2...-3....0...-1....3...-1...-1...-1....2...-4...-5...-2

%e ..2...-1....0....3....5....4....3...-3...-1....4....1...-4....4....0....0...-5

%e .-5....4...-2...-4...-4...-4...-3....4....2...-4...-4....3...-4...-3...-2....3

%e ..3...-4....5....5....1....5....1...-1...-3....4....3...-2...-1....5....3....1

%e .-3....2...-5...-5...-1...-2...-2....3....1...-3...-4....4...-4....1...-1....4

%e ..5...-2....3....5....2....5....2...-2...-4....5....4...-5....4....3....4...-3

%e ..1....0....1...-4...-1...-5...-1....0....2...-5....1....5...-1...-2....1....2

%K nonn

%O 1,2

%A _R. H. Hardin_ Nov 14 2011