Definition

A sequence is simply an ordered list of numbers, each following a specific rule. A series is what you get when you connect those numbers with a plus sign — the sum of the terms of a sequence. The notation $a_1, a_2, a_3, \dots$ represents the sequence, while $S_n = a_1 + a_2 + \dots + a_n$ denotes the series up to $n$ terms. Understanding this distinction …