Write a program that computes
4
⋅
∑
k
=
1
10
6
(
−
1
)
k
+
1
2
k
−
1
=
4
⋅
(
1
−
1
/
3
+
1
/
5
−
1
/
7
+
1
/
9
−
1
/
11
…
)
.
4\cdot \sum_{k=1}^{10^6} \frac{(-1)^{k+1}}{2k-1} = 4\cdot(1-1/3+1/5-1/7+1/9-1/11\ldots).