You could try to cast to an int, and repeat the question if it fails.
i = 1
while True:
timeNum = input("How many times do you want to repeat the sequence?")
try:
timeNum = int(timeNum)
break
except ValueError:
pass
while i <= timeNum:
...
i += 1
Though using try-catch for handling is taboo in some languages, Python tends to embrace the "ask for forgiveness, not permission approach". To quote the section on EAFP in the Python glossary:
Easier to ask for forgiveness than permission. This common Python coding style assumes the existence of valid keys or attributes and catches exceptions if the assumption proves false. This clean and fast style is characterized by the presence of many try and except statements.
