On ohtsuki.s invariants of integral homology 3-spheres

We provide some more explicit formulae to facilitate the computation of Ohtsuki.s rational invariants . n of integral homology 3-spheres extracted from Reshetikhin-TuraevSU(2) quantum invariants. Several interesting consequences will follow from our computation of .2. One of them says that .2 is always an integer divisible by 3. It seems interesting to compare this result with the fact shown by Murakami that .1 is 6 times the Casson invariant. Other consequences include some general criteria for distinguishing homology 3-spheres obtained from surgery on knots by using the Jones polynomial.