Showing what's behind the curtain

Find the 2000th hexagonal tile in which the differences between it and its 6 neighbors yield 3 primes.

The prime factorisation of binomial coefficients

Find the sum of the distinct square-free numbers in the first 51 rows of Pascal’s triangle.

Find fractions that cannot be cancelled down (resilient fraction).

Prime Subset Sums

Find the number of factors in an enormous factorial.

Investigating minimal repunits that divide by n.

Finding composite values, n, for which n−1 is divisible by the length of the smallest repunits that divide it.

Determining the first forty prime factors of a very large repunit.

Investigating which primes will never divide a repunit containing 10**n digits.