双质数是那些质数，并且两个质数之间相差两(2)的那些数。换句话说，孪生素数是素数差距为2的素数。
有时，术语“双生质”用于一对双生质。此的另一个名称是素生双胞胎或素对。通常，对(2，3)不被视为一对孪生素数。由于2是唯一的偶数质数，因此这对是唯一相差一个的质数对；因此，孪生素数与其他两个素数的间隔尽可能近。
前几个孪生素数对是：
(3, 5), (5, 7), (11, 13), (17, 19), (29, 31),
(41, 43), (59, 61), (71, 73), (101, 103),
(107, 109), (137, 139), …etc.事实：10，000以下有409个孪生素数。
除(3，5)外，每个双素数对都具有(6n – 1，1，6n + 1)的形式，其中包含自然数n。也就是说，两个素数之间的数字是6的倍数。
例子 ：
Input : n1 = 11, n2 = 13
Output : Twin Prime
Input : n1 = 23, n2 = 37
Output : Not Twin Prime先决条件：原始性测试|第一组(介绍和学校方法)
C++
// CPP program to check twin prime
#include
using namespace std;
// Please refer below post for details of this
// function
// https://goo.gl/Wv3fGv
bool isPrime(int n)
{
// Corner cases
if (n <= 1) return false;
if (n <= 3) return true;
// This is checked so that we can skip
// middle five numbers in below loop
if (n%2 == 0 || n%3 == 0) return false;
for (int i=5; i*i<=n; i=i+6)
if (n%i == 0 || n%(i+2) == 0)
return false;
return true;
}
// Returns true if n1 and n2 are twin primes
bool twinPrime(int n1, int n2)
{
return (isPrime(n1) && isPrime(n2) &&
abs(n1 - n2) == 2);
}
// Driver code
int main()
{
int n1 = 11, n2 = 13;
if (twinPrime(n1, n2))
cout << "Twin Prime" << endl;
else
cout << endl
<< "Not Twin Prime" << endl;
return 0;
} Java
// JAVA Code for Twin Prime Numbers
import java.util.*;
class GFG {
// Please refer below post for
// details of this function
// https://goo.gl/Wv3fGv
static boolean isPrime(int n)
{
// Corner cases
if (n <= 1) return false;
if (n <= 3) return true;
// This is checked so that we can skip
// middle five numbers in below loop
if (n % 2 == 0 || n % 3 == 0)
return false;
for (int i = 5; i * i <= n; i = i + 6)
if (n % i == 0 || n % (i + 2) == 0)
return false;
return true;
}
// Returns true if n1 and n2 are twin primes
static boolean twinPrime(int n1, int n2)
{
return (isPrime(n1) && isPrime(n2) &&
Math.abs(n1 - n2) == 2);
}
/* Driver program to test above function */
public static void main(String[] args)
{
int n1 = 11, n2 = 13;
if (twinPrime(n1, n2))
System.out.println("Twin Prime");
else
System.out.println("Not Twin Prime");
}
}
// This code is contributed by Arnav Kr. Mandal.Python3
# Python3 code to check twin prime
import math
# Function to check whether a
# number is prime or not
def isPrime( n ):
# Corner cases
if n <= 1:
return False
if n <= 3:
return True
# This is checked so that we
# can skip middle five numbers
# in below loop
if n%2 == 0 or n%3 == 0:
return False
for i in range(5, int(math.sqrt(n)+1), 6):
if n%i == 0 or n%(i + 2) == 0:
return False
return True
# Returns true if n1 and n2 are
# twin primes
def twinPrime(n1 , n2):
return (isPrime(n1) and isPrime(n2) and
abs(n1 - n2) == 2)
# Driver code
n1 = 137
n2 = 139
if twinPrime(n1, n2):
print("Twin Prime")
else:
print("Not Twin Prime")
# This code is contributed by "Sharad_Bhardwaj".C#
// C# Code for Twin Prime Numbers
using System;
class GFG {
// Please refer below post for
// details of this function
// https://goo.gl/Wv3fGv
static bool isPrime(int n)
{
// Corner cases
if (n <= 1) return false;
if (n <= 3) return true;
// This is checked so that we can skip
// middle five numbers in below loop
if (n % 2 == 0 || n % 3 == 0)
return false;
for (int i = 5; i * i <= n; i = i + 6)
if (n % i == 0 || n % (i + 2) == 0)
return false;
return true;
}
// Returns true if n1 and n2 are twin primes
static bool twinPrime(int n1, int n2)
{
return (isPrime(n1) && isPrime(n2) &&
Math.Abs(n1 - n2) == 2);
}
// Driver program
public static void Main()
{
int n1 = 11, n2 = 13;
if (twinPrime(n1, n2))
Console.WriteLine("Twin Prime");
else
Console.WriteLine("Not Twin Prime");
}
}
// This code is contributed by vt_m.PHP
Javascript
输出 ：
Twin Prime