a·rith·me·tic pro·gres·sion
noun/ˌærɪθmetɪk prəˈɡreʃn/
/ˌærɪθmetɪk prəˈɡreʃn/
(also arithmetic series
/ˌærɪθmetɪk ˈsɪəriːz/
/ˌærɪθmetɪk ˈsɪriːz/
)- a series of numbers that decrease or increase by the same amount each time, for example 2, 4, 6, 8
算术数列，等差数列（如 2、4、6、8）