28237
 13190
 39914
 81367
 8554
 61106
 67448
 39004
 22308
 16054
 71468
 60501
 100
 300
 59632
 90783
 5611
 1000
 69475
 69753
 10
 5
 582
 8
 36961
 5071
 20
 53213
 92775
 28738
 100000
 92280
 37944
 9
 2627
 7
 3

1028306548 224346172 2054738392 8539207488 94344524 4816051228 5867563092 1962150044 641839188 332342852 6587875268 4721174212 12600 115440 4586497300 10630118936 40580456 1286328 6225539588 6275533596 92 8 434692 52 1762017168 33141852 440 3652070664 11101694484 1065137992 12898363344 10983871880 1856988304 64 8885348 28 0
import java.util.*;
import java.io.*;
import java.math.BigInteger;
import java.util.regex.*;

public class Codeforces{
	
	static class MyScanner{
		BufferedReader br;
		StringTokenizer st;
		
		MyScanner(FileReader fileReader){
			br = new BufferedReader(fileReader);
		}
		
		MyScanner(){
			br = new BufferedReader(new InputStreamReader(System.in));
		}
		
		String nn(){
			while(st == null || !st.hasMoreElements()){
				try{
					st = new StringTokenizer(br.readLine());
				}catch(IOException e){
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}
		
		String nextLine(){
			String s = "";
			try{
				s = br.readLine();
			}catch(IOException e){
				e.printStackTrace();
			}
			return s;
		}
		
		int ni(){
			return Integer.parseInt(nn());
		}
		
		long nl(){
			return Long.parseLong(nn());
		}
		
		double nd(){
			return Double.parseDouble(nn());
		}
	}
	
	private static PrintWriter out;
	
	public static void main(String[] args) throws FileNotFoundException{
		
		// Input from file
		// File inputFile = new File("JavaFile.txt");
		// File outputFile = new File("JavaOutputFile.txt");
		// FileReader fileReader = new FileReader(inputFile);
		// Here it ends
			
		MyScanner sc = new MyScanner();
		// MyScanner sc = new MyScanner(fileReader);
		
		out = new PrintWriter(new BufferedOutputStream(System.out)); // Output to console
		// out = new PrintWriter(new PrintStream(outputFile)); // Output to file
		
		int n = sc.ni();
		long ans = 0;
		
		for(int i = 2; i <= n; i++){
			ans += 4 * i * (n / i - 1);
		}
		
		out.println(ans);
		
		out.close();
	}
}