C :

#include<stdio.h>
#include<math.h>
int find(int x){
	int sum=0,i,t=sqrt(x);
	for ( i=2; i<=t; i++)
		if (x%i==0) sum+=i+x/i;
	if (t*t==x) sum-=t;
	return sum;
}

int main(){
	int n,a,b,c;
	scanf("%d",&n);
	for ( a=2; a<=n; a++){
		b=find(a); c=find(b);
		if (a==c && a!=b && b<=n)
		 printf("%d %d\n",a,b);
	}
	return 0;
}

C++ :

#include <iostream>
#include <cmath>
using namespace std;
int sum(int n){
	int s,i;
	s=0;
	for(i=2;i<=sqrt(n);i++){
		if(n%i==0){
			if(i==n/i){
				s=s+i;
			}else{
				s=s+i+n/i;
			}
		}
	}
	return s;
}
void shudui(int n){
	int i,s;
	for(i=2;i<=n;i++){
		s=sum(i);
		if(sum(s)==i&&i!=s&&s<=n){
			cout<<i<<" "<<s<<endl;
		}
	}
}
int main(){
	int n;
	cin>>n;
	shudui(n);
}

Pascal :

var
    a:array[0..200000] of longint;
    i,j,n,s:longint;
begin
    readln(n);
    for i:=2 to 2000 do
    begin
        s:=0;
        for j:=2 to i-1 do
            if i mod j=0 then inc(s,j);
        a[i]:=s;
    end;
    for i:=2 to n do
        if (a[a[i]]=i)and(a[i]<>i)and(a[i]<=n) then writeln(i,' ',a[i]);
end.

Java :

import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		qinMi(n);
		
	}
	public static int forSum(int n) {
		int sum = 0;
		for(int i = 2; i <= n / 2; i++ ) {
			
			if(n % i == 0) {
				sum += i;
			}
		}
		return sum;
		
	}
	
	public static void qinMi(int n) {
		int sum1 = 0;
		int sum2 = 0;
		for(int i = 2; i <= n ; i++ ) {
			sum1 = forSum(i);
			for(int k= 2; k <= n ; k++ ) {
				sum2 = forSum(k);
				if(sum1 == k && i == sum2 && i != k) {
					System.out.println(i + " " + k);
				}
			}
		}
	}
	
	
}

Python :

def yinZiHe(n):
    s=0
    for i in range(2,n):
        if n%i==0:
            s+=i
    return s
n=int(input())
for i in range(2,n+1):
       # i的因子和等于b b的因子和等于i
    if yinZiHe(yinZiHe(i))==i and yinZiHe(i)!=i and yinZiHe(i)<=n:
        print(i,yinZiHe(i))