Here the code for get three digit value 'n' and calculate r=2^n+1 then find that value 'r' is a prie or not, here i like store the integer value 'r' without exponential function and big Integer, please make a great help to me.
thanks in advance..
import java.*;
import java.io.*;
import java.io.IOException.*;
import java.math.*;
public class primenumber extends power{
public static void main(String a[])throws IOException {
//get input
power ob=new power();
DataInputStream dis=new DataInputStream(System.in);
System.out.println(" Enter three digit number n:");
String nu=dis.readLine();
int n=Integer.parseInt(nu);
long nvalue=ob.powerr(n);
//find prime
long r;
int primevalue=0,i,j=0;
long factors[]=new long[100];
for(i=2;i<=nvalue;i++)
{r=nvalue%i;
if(r==0)
{
if(i!=nvalue)
{factors[j]=i;
j++;
primevalue=1;
//System.out.println("not prime");
}//inner if
else
{
//System.out.println("prime");
}
}//outer if
}//for ends
System.out.println("Given number is"+n+"");
System.out.println("Prime calculation for"+nvalue+"");
System.out.println("power value is"+nvalue+"");
if(primevalue!=1){
System.out.println("The number "+nvalue+" is prime");
}
else{
System.out.println("The number "+nvalue+" is not a prime");
System.out.println("factors");
for(int k=0;k<=j-1;k++)
System.out.print("," +factors[k]);
}//primevalueif
}//main end here
}//class end here
class power {
//find power
final int two=2;
long powvalue=1 , i;
long powerr(int x){
int n=x;
for(i=1;i<=n+1;i++)
{powvalue*=two;
}
return powvalue;
};
}
