  Starting with an infinite set of non linear Equations for the Li-Keiper
coefficients, we first specify a lower bound emerging from the infinite set and
give a characterization of it. Then, we propose a possible new upper and lower
bound for the coefficients in few of the partitions occurring in the cluster
functions furnishing in a nonlinear way the coefficients. A numerical
experiment up to n=15 confirms the proposed bounds and an experiment, i.e. the
counting of the zeros in the binary representation of an integer for a constant
related to the Glaisher-Kinkelin constant is also given up to n=32.
