Proposition 3.9.
Assuming that:
σ
>
1
and
t
∈
ℝ
Then
3
ζ
′
ζ
(
σ
)
+
4
Re
(
ζ
′
ζ
(
σ
+
i
t
)
)
+
Re
(
ζ
′
ζ
(
σ
+
2
i
t
)
)
≤
0
.
(∗∗)