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Number of arrays of n integers in -5..5 with sum zero and equal numbers of elements greater than zero and less than zero
1

%I #5 Mar 31 2012 12:36:45

%S 1,11,31,571,2651,42821,263201,3688091,27050251,343631641,2832605381,

%T 33728463781,300829918741,3434173821131,32324196127871,

%U 359135576566811,3508242939891611,38316667628995001,384106315200918101

%N Number of arrays of n integers in -5..5 with sum zero and equal numbers of elements greater than zero and less than zero

%C Column 5 of A201811

%H R. H. Hardin, <a href="/A201808/b201808.txt">Table of n, a(n) for n = 1..210</a>

%e Some solutions for n=6

%e ..0...-4....2...-4....4...-3....3...-5...-4...-1...-4....3....2...-4....2...-1

%e ..4....4...-1....4...-3....2...-3....5....4...-4...-4...-2...-4....0....5...-4

%e ..0...-1...-2....3....3...-5....0...-5...-1....1...-4...-1...-1....3...-3....1

%e ..2...-4....2...-3....1....5....0....4....2....2....5....1....4...-4...-2...-3

%e .-2....2...-4...-3...-1...-3....3....5....2...-1....3...-5....2....5....2....5

%e .-4....3....3....3...-4....4...-3...-4...-3....3....4....4...-3....0...-4....2

%K nonn

%O 1,2

%A _R. H. Hardin_ Dec 05 2011