Find the maximum 16-digit string for a “magic” 5-gon ring.
Find the value of n ≤ 1,000,000 for which n/φ(n) is a maximum.
Investigate values of n for which φ(n) is a permutation of n.
Listing reduced proper fractions in ascending order of size.
How many elements would be contained in the set of reduced proper fractions for d ≤ 1,000,000?
Find the number of fractions that lie between 1/3 and 1/2 in a sorted set of reduced proper fractions.
Determine the number of factorial chains that contain exactly sixty non-repeating terms.
Count the different lengths of wire that can form a right angle triangle in only one way.
How many different ways can one hundred be written as a sum of at least two positive integers?
Find the first value which can be written as the sum of primes in over five thousand different ways.