Evaluate

**Solution**

We are invoking two lemmata first:

**Lemma 1: **It holds that .

*Proof: *

If we call then and as a consequence we have that

proving lemma 1.

**Lemma 2: **It holds that .

*Proof:*

proving Lemma 2.

Hence for the value of we have successively

**Note: **In general it holds that

as well as