ge·o·met·ric pro·gres·sion
noun/ˌdʒiːəˌmetrɪk prəˈɡreʃn/
/ˌdʒiːəˌmetrɪk prəˈɡreʃn/
(also geometric series)
(mathematics)- a series of numbers in which each is multiplied or divided by a fixed number to produce the next, for example 1, 3, 9, 27, 81
几何数列；等比数列