In science, a testable prediction to explain observations is known as a(n)

What Is a Testable Prediction? In science, an educated guess about the cause of a natural phenomenon is called a hypothesis. It's essential that hypotheses be testable and falsifiable, meaning they can be tested and different results will ensue depending on whether the hypothesis is true or false.

a sequence is a function whose domain is the set of natural numbers.

natural numbers are all the negative and positive integers