# An occult sum

**Calculus**Level 5

If the value of the above sum can be expressed in the form \[\sqrt { { e }^{ \varphi } } \cos { \left( \frac { \beta \pi +\gamma \sqrt { \alpha \left( \gamma -\sqrt { \gamma } \right) } }{ \delta } \right) }\] with \(\alpha\), \(\beta\), and \(\gamma\) positive divisors of \(\delta\); \(\alpha\) a divisor of \(\beta\); and \(\alpha\) and \(\gamma\) prime numbers, find \(\dfrac { \beta \times \delta }{ \alpha \times \gamma }\).

**Notations**:

\(e\) denotes Euler's number, the base of the natural logarithm.

\(\varphi\) represents the golden ratio, or \(\dfrac { 1+\sqrt { 5 } }{ 2 }\).

###### This problem is original.

###### Image Credit: *Pentacle 1* by Nyo, Wikipedia.

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