Sum of Reciprocals of Primes is Divergent/Lemma

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Theorem

Let $C \in \R_{>0}$ be a (strictly) positive real number.


Then:

$\ds \lim_{n \mathop \to \infty} \paren {\map \ln {\ln n} - C} = + \infty$


Proof

Fix $c \in \R$.

It is sufficient to show there exists $N \in \N$, such that:

$(1): \quad n \ge N \implies \map \ln {\ln n} - C > c$


Proceed as follows:

\(\ds \map \ln {\ln n} - C\) \(>\) \(\ds c\)
\(\ds \leadstoandfrom \ \ \) \(\ds \ln n\) \(>\) \(\ds \map \exp {c + C}\) Definition of Exponential
\(\ds \leadstoandfrom \ \ \) \(\ds n\) \(>\) \(\ds \map \exp {\map \exp {c + C} }\) Definition of Exponential


Let $N \in \N$ such that $N > \map \exp {\map \exp {c + C} }$.

By Logarithm is Strictly Increasing it follows that $N$ satisfies condition $(1)$.

Hence the result.

$\blacksquare$