Who discovered the harmonic sequence?

The harmonic sequence, which consists of the reciprocals of natural numbers (1, 1/2, 1/3, 1/4, ...), does not have a single discoverer, as it emerged from early mathematical developments in various cultures. However, the concept of harmonic numbers and related sequences can be traced back to ancient Greek mathematicians like Nicomachus and later to Indian mathematicians. The harmonic series was studied more rigorously in the context of calculus by mathematicians like Leonhard Euler in the 18th century.