What is arithmetic ratio series?

Sequence a(n) is called arithmetic progression, if a (n+1) = a (n)+d.

If a series starts from the second term and the difference between each term and its previous term is equal to the same constant, this series is called arithmetic progression, and this constant is called arithmetic progression's tolerance, which is usually expressed by the letter D, especially when d= 1, a(n) is a constant series.

Definition of geometric series:

Sequence a(n) is called geometric series, if a(n+ 1) = a(n) * q, where q is not equal to 0.

If a series starts from the second term and the ratio of each term to the previous term is equal to the same constant, this series is called geometric series.

This constant is called the common ratio of geometric series and is usually expressed by the letter q (q≠0). Especially when q= 1, a(n) is a constant sequence.

I hope it helps you ~