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Number of -2..2 arrays x(0..n-1) of n elements with zero sum and no element more than one greater than the previous
1

%I #6 Mar 31 2012 12:36:37

%S 1,3,8,23,66,192,575,1739,5307,16304,50381,156408,487398,1523663,

%T 4776107,15006513,47247134,149023605,470794024,1489462276,4718330397,

%U 14964219411,47509518289,150982994162,480243297965,1528796563830,4870415108094

%N Number of -2..2 arrays x(0..n-1) of n elements with zero sum and no element more than one greater than the previous

%C Column 2 of A199847

%H R. H. Hardin, <a href="/A199841/b199841.txt">Table of n, a(n) for n = 1..200</a>

%e Some solutions for n=6

%e ..2...-1....2....1....2....1....1....1....1...-1....2....1....1....1....1....1

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

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

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

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

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

%K nonn

%O 1,2

%A _R. H. Hardin_ Nov 11 2011