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%I #7 Mar 31 2012 12:36:48
%S 1,3,15,29,95,255,747,2215,6649,19967,60145,182003,554625,1691547,
%T 5175093,15875649,48789933,150258301,463501341,1431832723,4429155217,
%U 13716674493,42524970155,131966196475,409893633219,1274208141011
%N Number of zero-sum -3..3 arrays of n elements with first through third differences also in -3..3
%C Column 3 of A202511
%H R. H. Hardin, <a href="/A202506/b202506.txt">Table of n, a(n) for n = 1..210</a>
%e Some solutions for n=7
%e .-3...-1...-1...-3....0...-1...-2...-1....2....0....3....0...-3....0....0...-1
%e .-2....0...-1...-1....0...-1....1....1....0...-1....1...-1....0....0....0....2
%e .-1....0...-1...-1...-1...-1....1....1...-2....0...-1...-1....1...-1....0....2
%e .-1...-1....0....0...-1....0....1....0...-2....0...-3....1....1...-2...-1....1
%e ..1...-1....1....1....0....1....0...-1...-1....0...-2....2....1...-1....0....0
%e ..3....0....2....2....1....1....0...-1....1....0....0....1....0....1....1...-2
%e ..3....3....0....2....1....1...-1....1....2....1....2...-2....0....3....0...-2
%K nonn
%O 1,2
%A _R. H. Hardin_ Dec 20 2011