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.
$\blacksquare$