Exercise 05-1: Calculate the sum 1^2 + 2^2 + ... 100^2
Exercise 05-2: Reimplement 'replicate' using a list comprehension
Exercise 05-3: Implement 'pyths' using a list comprehension

'pyths' produces the list of all pythagorean triples (x^2 + y^2 = z^2)
whose components are at most a given limit n
Exercise 05-4: Implement 'perfects' using a list comprehension

'perfects' produces the list of all perfect numbers up to a given limit n
A positive integer is perfect if it equals the sum of its factors
(excluding the number itself)
Exercise 05-5: Nested list comprehensions
Exercise 05-6: Reimplement 'positions' using 'find'

'positions' produces the list of all positions at which
a value x occurs in a list xs
Exercise 05-7: Implement 'scalarProduct'
Exercise 05-8: Caesar cipher to also handle upper-case letters
Extra exercise 05-1: Nested list comprehensions
Extra exercise 05-2: Nested list comprehensions
Extra exercise 05-3: Implement 'riffle'

Takes 2 lists (same length) and interleaves their elements in turn
Extra exercise 05-4: Implement 'divisors'