  Results of 75As NMR and NQR measurements are reported for superconducting
samples of LaFeAsO1-xFx with various x values. The x dependent widths of the
superconducting transition and those of the NQR spectra indicate that the
optimally doped LaFeAsO1-xFx sample with the superconducting transition
temperature Tc ~28 K has the smallest width or smallest inhomogeneity of the
superconducting order parameter \Delta. In the analyses of the temperature (T)
dependence of the NMR longitudinal relaxation rate 1/T1, we have tried to use a
simple relation 1/T1 ~ T^n to see how fast 1/T1 decreases when the
superconducting order parameter grows. The relation holds rather well in the T
region of ~0.3Tc < T =< Tc, and n varies from 2.5-6 with varying x, having the
maximum value 5-6 at the optimal x. These results indicate that the x
dependence of n originates from the spatial distribution of \Delta, and that
the T^{5-6} behavior is considered to be intrinsic to this system.
