Sequences and Series

A sequence is an ordered list of numbers. A series is the sum of a sequence.

Arithmetic Sequence

a_n = a_1 + (n-1)d
            

Geometric Sequence

a_n = a_1 r^{n-1}
            

Sum Formulas

• Arithmetic: S_n = n/2 (a_1 + a_n)
• Geometric: S_n = a_1 (1 - r^n)/(1 - r)