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A200555 Number of -n..n arrays x(0..4) of 5 elements with zero sum and nonzero second differences. 1

%I

%S 26,280,1184,3396,7778,15476,27806,46346,72902,109528,158422,222162,

%T 303412,405134,530518,683014,866156,1083954,1340420,1639900,1986968,

%U 2386470,2843276,3362828,3950486,4611980,5353268,6180592,7100158,8118840

%N Number of -n..n arrays x(0..4) of 5 elements with zero sum and nonzero second differences.

%C Row 3 of A200553.

%H R. H. Hardin, <a href="/A200555/b200555.txt">Table of n, a(n) for n = 1..200</a>

%F Empirical: a(n) = a(n-1) +2*a(n-2) -3*a(n-4) -3*a(n-5) +3*a(n-6) +3*a(n-7) -2*a(n-9) -a(n-10) +a(n-11).

%F Empirical g.f.: 2*x*(13 + 127*x + 426*x^2 + 826*x^3 + 1046*x^4 + 912*x^5 + 544*x^6 + 205*x^7 + 37*x^8 + 4*x^9) / ((1 - x)^5*(1 + x)^2*(1 + x + x^2)^2). - _Colin Barker_, May 21 2018

%e Some solutions for n=3:

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

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

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

%e ..2....2....1...-2....1...-3....1...-2....2...-1....2....1...-1...-3....1....2

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

%Y Cf. A200553.

%K nonn

%O 1,1

%A _R. H. Hardin_, Nov 19 2011

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Last modified June 25 22:13 EDT 2022. Contains 354868 sequences. (Running on oeis4.)