Given an integer N, the task is to find the count of all the primes below N which can be expressed as the sum of two primes.
Input: N = 6
5 is the only such prime below 6.
2 + 3 = 5.
Input: N = 11
Approach: Create an array prime where prime[i] will store whether i is prime or not using Sieve of Eratosthenes. Now for every prime from the range [1, N – 1], check whether it can be expressed as the sum of two primes using the approach discussed here.
Below is the implementation of the above approach:
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- Count primes that can be expressed as sum of two consecutive primes and 1
- Check if an integer can be expressed as a sum of two semi-primes
- Count of primes in a given range that can be expressed as sum of perfect squares
- Find the sum of all Truncatable primes below N
- Print all safe primes below N
- Elements of Array which can be expressed as power of prime numbers
- Elements of Array which can be expressed as power of some integer to given exponent K
- Check if a prime number can be expressed as sum of two Prime Numbers
- Check if a number can be expressed as sum two abundant numbers
- Check if a number can be expressed as sum of two Perfect powers
- Count prime numbers that can be expressed as sum of consecutive prime numbers
- Check if a given number can be expressed as pair-sum of sum of first X natural numbers
- Count numbers which can be represented as sum of same parity primes
- Sum of the multiples of two numbers below N
- Count of numbers below N whose sum of prime divisors is K
- Check if a number can be expressed as a sum of consecutive numbers
- Find ways an Integer can be expressed as sum of n-th power of unique natural numbers
- Find the prime numbers which can written as sum of most consecutive primes
- Minimum numbers needed to express every integer below N as a sum
- Find the sum of all multiples of 2 and 5 below N
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