Factors and Multiples

Question

In 1845, the French mathematician Joseph Bertrand conjectured that between any whole number greater than 1 and its double there exists at least one prime. After 50 years, this conjecture was proved true by the Russian mathematician Pafnuty Chebyshev.

 

For each number greater than 8 and less than 18, find the smallest and the largest prime between the number and its double.

 

Number	Double	Primes
9	18
10	20
11	22
12	24
13	26
14	28
15	30
16	32
17	34

Answer 1

A simple list of known primes between 11 and 31 would do here

For example between 9 and 18 exist 11, 13, 17 as primes.

Some of these numbers may have the same primes between them and their doubles as others.

By the way there are a few obvious primes within the table

Make yourself a list of primes between 11and 31 and use them in the table where appropriate.