cp's OEIS Frontend

A201810 Number of arrays of n integers in -7..7 with sum zero and equal numbers of elements greater than zero and less than zero.

%I A201810 #7 Jul 22 2025 16:21:34
%S A201810 1,15,43,1471,7071,207621,1355145,33222463,266948431,5714583505,
%T A201810 53305896645,1032485634181,10748736159253,193347106894215,
%U A201810 2184638624782083,37202261536824063,447056372628222463
%N A201810 Number of arrays of n integers in -7..7 with sum zero and equal numbers of elements greater than zero and less than zero.
%C A201810 Column 7 of A201811
%H A201810 R. H. Hardin, <a href="/A201810/b201810.txt">Table of n, a(n) for n = 1..210</a>
%e A201810 Some solutions for n=5
%e A201810 .-5....2...-3...-5...-3....2....4....1...-7....6....0....3....4....0...-2...-6
%e A201810 ..1....3....0....5....2...-3....6...-4....0...-3....1...-4....0....7...-5....3
%e A201810 ..0....0...-5...-4....6...-3....0....0....7....3...-2....0....6....1....3....0
%e A201810 .-3...-4....5....4...-5....4...-4...-4....2...-6...-1....2...-7...-1....4....5
%e A201810 ..7...-1....3....0....0....0...-6....7...-2....0....2...-1...-3...-7....0...-2
%K A201810 nonn
%O A201810 1,2
%A A201810 _R. H. Hardin_ Dec 05 2011