#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <list>
#include <cmath>

using namespace std;

#define EPSILON (1e-12)
#define EQ(x,y) (fabs((x) - (y)) < EPSILON)

int p, q, a, n;
int x[10];
int cnt;

void test(int k){
  double d = 0.0;
  for(int i=1; i<=k; i++){
    d += ((double)1/(double)x[i]);
  }
  if(EQ((double)p/(double)q , d)){
    //    cout << n << ":" << x[1] << "," << x[2] << "," << x[3] << endl;  
    cnt++;
  }
}


void recur(int k, int base){
  if(k==n+1){
    return;
  }else{
    for(int i=x[k-1]; i * base <= a; i++){
      x[k] = i;
      test(k);
      recur(k+1, base*i);
    }
  }
}

int main()
{
  while(cin >> p >> q >> a >> n){
    if(p == 0 && q == 0 && a == 0 && n == 0){ return 0; }
    x[0] = 1;
    cnt = 0;
    recur(1, 1);
    cout << cnt << endl; 
  }
  return 0;
}