Yet another of Euler's Formulas . On the left, we sum up the reciprocals of all integers n starting with 1 raised to the real power of s. Such a sum is known in Calculus as an infinite series or just series.
Some series are divergent , some convergent .
Convergent series are ascribed a unique number known as the sum of a series. Thus it has a sum. Euler's formula claims that the same number can be found as an infinite product as expressed on the right. Except that on the right there is one term for every prime number. As was the case with the series, some infinite product diverge, some converge.