find the integer factorization using pollard's p-1 method.

this code is execuate for n=299.but fail for n=20.where is the problem?

clc;clear all;
n=input('Enter a composite number: ');
p=2;
i=2;
k=1;
    d(1)=gcd(p-1,n);
     d1(k)=n/d(k);
    while gcd(p-1,n)==1
    p=rem(p^i,n);
    i=i+1;
    d(k)=gcd(p-1,n);
      d1(k)=n/d(k);
    if isprime(d1(k))==true && isprime(d(k))==true
        break;
     elseif isprime(d(k))==true && isprime(d1(k))==false
        n=d1(k);
        k=k+1;
        p=2;
        i=2;
    else
    end
    end
disp(d)
disp(d1)

[the cyclist]

Can you share the source that you used for the algorithm? I looked at this article Wikipedia, but your code doesn't seem to correspond to the algorithm there.

[Foysal Hossain]

https://www.geeksforgeeks.org/pollard-p-1-algorithm/