Find a set of five primes for which any two primes concatenate to produce another prime.
Find the sum of the only set of six 4-digit figurate numbers with a cyclic property.
Find the smallest cube for which exactly five permutations of its digits are cube.
How many n-digit positive integers exist which are also an nth power?
How many continued fractions for N ≤ 10000 have an odd period?
Find the sum of digits in the numerator of the 100th convergent of the continued fraction for e.
Investigate the Diophantine equation x2 − Dy2 = 1.
Using an efficient algorithm find the maximal sum in the triangle?
What is 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.