cp's OEIS Frontend

A201808 Number of arrays of n integers in -5..5 with sum zero and equal numbers of elements greater than zero and less than zero.

%I A201808 #7 Jul 22 2025 16:21:21
%S A201808 1,11,31,571,2651,42821,263201,3688091,27050251,343631641,2832605381,
%T A201808 33728463781,300829918741,3434173821131,32324196127871,
%U A201808 359135576566811,3508242939891611,38316667628995001,384106315200918101
%N A201808 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 A201808 Column 5 of A201811
%H A201808 R. H. Hardin, <a href="/A201808/b201808.txt">Table of n, a(n) for n = 1..210</a>
%e A201808 Some solutions for n=6
%e A201808 ..0...-4....2...-4....4...-3....3...-5...-4...-1...-4....3....2...-4....2...-1
%e A201808 ..4....4...-1....4...-3....2...-3....5....4...-4...-4...-2...-4....0....5...-4
%e A201808 ..0...-1...-2....3....3...-5....0...-5...-1....1...-4...-1...-1....3...-3....1
%e A201808 ..2...-4....2...-3....1....5....0....4....2....2....5....1....4...-4...-2...-3
%e A201808 .-2....2...-4...-3...-1...-3....3....5....2...-1....3...-5....2....5....2....5
%e A201808 .-4....3....3....3...-4....4...-3...-4...-3....3....4....4...-3....0...-4....2
%K A201808 nonn
%O A201808 1,2
%A A201808 _R. H. Hardin_ Dec 05 2011