A periodic function f(t) has the exponential series ƒ(t)

A periodic function f(t) has the exponential series
ƒ(t) = A + 2A + e^-j3ω + e^-jω + e^jω + e^j3ω .........
2 π² (- 3)² (- 1)² 1² 3²

The trigonometric form of the series is

ƒ(t) =	A	+	2A	Σ	cos k ω₀t	for all integers
	2		π		k²

ƒ(t) =	A	+	2A	Σ	cos k ω₀t	for k odd
	2		π²		k²

ƒ(t) =	A	+	4A	Σ	cos k ω₀t	for k odd
	2		π²		k²

ƒ(t) =	A	+	4A	Σ	cos k ω₀t	for k even
	2		π²		k²