function used = genused(noused)

used = zeros(8,8);

D = 2;
step = -1;
m = 1;
n = 2;
while sum(sum(used)) < noused
    if m == D
        used(D,1) = 1;
        D = D+1;
        n = 1;
        step = -step;
    elseif n == D
        used(1,D) = 1;
        D = D+1;
        step = -step;
        m = 1;
    else
        used(m,n) = 1;
    end
    m = m+step;
    n = n-step;
end