#include <iostream>
using namespace std;

int P, Q, MaxSeki, Count;

bool f(int shi, int bo, int start, int dep, int check){
  
  //cout << "!" << endl;
  //cout << shi << " " << bo << endl;
  
  if(check > MaxSeki) {
    return false;
  }
  if(shi * Q == bo * P) {
    Count++;
    //return true;
  }
  if(shi * Q > bo * P) {
    return false;
  }
  if(dep == 0) {
    return false;
  }
  
  for(int i = start; i <= 6000; i++) {
    
    f(i*shi + bo, bo*i, i, dep - 1, check * i);
  }
  
  return true;
}

int main(){

  int n;
  while(cin >> P >> Q >> MaxSeki >> n) {

    if(P == 0 && Q == 0 && MaxSeki == 0 && n == 0)
      break;

    Count = 0;
    f(0, 1, 1, n, 1);

    cout << Count << endl;
  }

  return 0;
}