cp's OEIS Frontend

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

%I A200555 #8 May 21 2018 11:26:53
%S A200555 26,280,1184,3396,7778,15476,27806,46346,72902,109528,158422,222162,
%T A200555 303412,405134,530518,683014,866156,1083954,1340420,1639900,1986968,
%U A200555 2386470,2843276,3362828,3950486,4611980,5353268,6180592,7100158,8118840
%N A200555 Number of -n..n arrays x(0..4) of 5 elements with zero sum and nonzero second differences.
%C A200555 Row 3 of A200553.
%H A200555 R. H. Hardin, <a href="/A200555/b200555.txt">Table of n, a(n) for n = 1..200</a>
%F A200555 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 A200555 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 A200555 Some solutions for n=3:
%e A200555 ..3...-2...-3....0...-2....3...-2....2...-3...-2...-1....2....1....2...-2....3
%e A200555 ..0...-3....2...-1....3...-1...-2....2....3....3....1....2....1...-2....1...-1
%e A200555 .-2....1....1....3....0....1....2...-1....0...-3...-2...-2...-2....2...-3...-3
%e A200555 ..2....2....1...-2....1...-3....1...-2....2...-1....2....1...-1...-3....1....2
%e A200555 .-3....2...-1....0...-2....0....1...-1...-2....3....0...-3....1....1....3...-1
%Y A200555 Cf. A200553.
%K A200555 nonn
%O A200555 1,1
%A A200555 _R. H. Hardin_, Nov 19 2011