The sequence "1, 2, 3, 4, 6, 9, 12, 18" consists of numbers that are all factors of 36. Factors are whole numbers that can be multiplied together to produce another number. In this case, each number can divide 36 without leaving a remainder. These numbers can also be categorized as part of the set of positive integers. They are used in various mathematical concepts, including division, multiplication, and factorization. Understanding factors is essential in areas such as algebra and number theory.