[HaBo]

#include <iostream>
 
using namespace std;
 
bool isPrim(int n){
 
 if(n == 0)
  return false;
 
 for (int i = 2; i<  n; i++){
 
  if ( ( (n % i) == 0) && (i != n) && (i != 1) )
   return false;
 };
 
 return true;
 
};
 
 
int main(){
 
 int start, end, pim[2];
 
 prim[0] = 0;
 prim[1] = 0;
 
 cout << "START: ";
 cin >> start;
 cout << "END: ";
 cin >> end;
 cout << endl;
 
 for (int i = start; i <= end; i++){
 
  if (isPrim(i) == true){
 
   if(prim[0] == 0){
    prim[0] = i;}
   else prim[1] = i;
 
   if ( (prim[0] != 0) && (prim[1] != 0) ){
 
    if( (prim[1] - prim[0]) == 2){
     cout << prim[0] << " - " << prim[1] << "\n";
    };
    prim[0] = prim[1];
    prim[1] = 0;
   };
  };
 };
 
 return 0;
 
};

#include <stdio.h>
#include <math.h>

unsigned long int find_next_prime(unsigned long int);

int main( void )
{
    unsigned long int von, first, second;
    unsigned int anz, zaehler;

    printf("\n\nVon welcher Zahl an sollen Primzahlenpaare gesucht werden?\n");
    scanf("%lu", &von);
    printf("Wie viel Primzahlenpaare sollen gefunden werden?\n");
    scanf("%u", &anz);

    zaehler = 0;

    while(zaehler < anz)
    {
        first = find_next_prime(von);
        second = find_next_prime(first);
        if(second - first == 2)
        {
            zaehler++;
            printf("\n%9u: %11lu    || %11lu", zaehler, first, second);
        }
        von = first;
    }

    getchar();
    printf("\n\n\n  DANKE und TSCHÜSS !!!\n\n  Press Enter to Exit ;)  ....  ");
    getchar();

    return 0;
}

unsigned long int find_next_prime(unsigned long int x)
{
        bool its_a_prime = true;
        if( x % 2 == 0 ) x++;
        if( x < 3 ) return 3;
        else
        {
                do
                {
                        its_a_prime = true;
                        x+=2;
                        for(unsigned long int i = 2; i < sqrt(x) + 1; i++)
                        {
                                if( (x % i) == 0 )
                                {
                                        its_a_prime = false;
                                }
                        }
                }while( !its_a_prime );
        }
        return x;
}

import math
def primepair(start,end):
	primes = [2]
	for i in range(3,end+1,2):
		for x in primes:
			if x>math.sqrt(i):
				continue
			if i%x==0:
				break
		else:
			if((i-primes[-1]==2)&(primes[-1]>=start)):
				print("%d - %d" % (primes[-1], i))
			primes.append(i)

#!/usr/bin/python

startwert = 3
endwert = input("Endwert: ")
zahl = 5
test = 0

print startwert, " - ", zahl

while  zahl < endwert:
  test = zahl % 3
  test2 = startwert % 3
  if test != 0 and test2 != 0:
    print startwert, " - ", zahl
  startwert = startwert + 2
  zahl = zahl + 2

3  -  5
5  -  7
7  -  9 <--
-->9  -  11
11  -  13
13  -  15<--
-->15  -  17
17  -  19
19  -  21<---

5  -  7
11  -  13
17  -  19
23  -  25<--- (5*5)
29  -  31
(5*7)--->35  -  37
41  -  43
47  -  49 <--- 7 * 7
53  -  55<--- 5*11