%I #7 Jun 07 2021 13:59:14
%S 142,1832,22276,278906,3513884,44716536,572857272,7380022092,
%T 95496980144,1240352594210,16161267003100,211148128583658,
%U 2765181621011902,36287540439791446,477071904597059874,6282247056373911518
%N Number of -7..7 arrays x(0..n+1) of n+2 elements with zero sum and nonzero first and second differences.
%C Column 7 of A200454.
%H R. H. Hardin, <a href="/A200453/b200453.txt">Table of n, a(n) for n = 1..97</a>
%e Some solutions for n=3
%e .-1...-4....0....7....5....5....6...-4....2....0...-1...-5....4....2...-6...-6
%e .-3....3....2....0...-1....2...-2....6....3....4....2....6...-5....3...-1....7
%e ..4....4...-5...-1...-2...-6...-4....4...-5...-1...-3....1....1...-4....1...-6
%e .-5...-3....3...-4...-4...-4...-7....0...-1...-4....4...-5...-3....3....6....2
%e ..5....0....0...-2....2....3....7...-6....1....1...-2....3....3...-4....0....3
%K nonn
%O 1,1
%A _R. H. Hardin_ Nov 18 2011