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%I #8 Aug 14 2018 08:57:14
%S 13,169,1105,9633,78273,653185,5407233,44890625,372332545,3089205249,
%T 25628045313,212618141697,1763923329025,14633929146369,
%U 121406394466305,1007215475032065,8356090693812225,69324049716609025,575128245018558465
%N Number of -6..6 arrays of length n with the sum ahead of each element differing from the sum following that element by 6 or less.
%C Column 6 of A221967.
%H R. H. Hardin, <a href="/A221965/b221965.txt">Table of n, a(n) for n = 1..90</a>
%F Empirical: a(n) = 7*a(n-1) + 18*a(n-2) - 56*a(n-3) - 48*a(n-4) + 112*a(n-5) + 32*a(n-6) - 64*a(n-7).
%F Empirical g.f.: 13*x*(1 + 6*x - 24*x^2 - 32*x^3 + 80*x^4 + 32*x^5 - 64*x^6) / ((1 - x)*(1 - 6*x - 24*x^2 + 32*x^3 + 80*x^4 - 32*x^5 - 64*x^6)). - _Colin Barker_, Aug 14 2018
%e Some solutions for n=6:
%e .-3...-6....0...-6....3....0....0....0....0....0....0...-3...-6....3...-6...-6
%e ..3....5...-5...-3....0....3....0...-3...-3...-3...-2....0....1...-3....5....3
%e .-2...-1....1....5...-3...-3...-1....0....2....3...-3....0...-3....1....0...-3
%e ..3...-3....6...-1....2...-4....4...-4....3....0....6....0....6...-5...-2....4
%e .-5....3...-3...-1...-4....6...-5....4...-1....2...-5...-1...-2....4....1...-2
%e ..0...-2...-3...-3....5...-1....3...-3....0...-1...-2...-5...-6...-1....1...-3
%Y Cf. A221967.
%K nonn
%O 1,1
%A _R. H. Hardin_, Feb 01 2013
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