SASMO 2016 Secondary 1 (Grade 7) Contest Question 17

A prime number p is a Sophie Germain Prime if both p and 2 x p + 1 are prime

numbers. Number 5 is a Sophie Germain Prime since both 5 and 11 (= 2x 5 + 1)

are prime numbers. How many Sophie Germain Primes less than 60 are there?