EN
We present monotonicity theorems for index functions of N-fuctions, and obtain formulas for exact values of packing constants. In particular, we show that the Orlicz sequence space $l^{(N)}$ generated by the N-function N(v) = (1+|v|)ln(1+|v|) - |v| with Luxemburg norm has the Kottman constant $K(l^{(N)}) = N^{-1}(1)/N^{-1}(1/2)$, which answers M. M. Rao and Z. D. Ren's [8] problem.