/**
 *  Unit Fraction Partition (PKU 1980)
 *  by Kenji Inoue, 2006-12-31
 **/

#include <iostream>

using namespace std;

#define EPS (1e-8)
#define EQ(a,b) ((a) - EPS < (b) && (b) < (a) + EPS)

int p, q, a;
double lhs; // left hand side

int solve(int n, int d, int prod, double sum) {
  int cnt=0;
  for (int i=d; prod*i<=a; i++) {
    double rhs = sum + 1.0/i; // right hand side
    if (lhs < rhs - EPS) { continue; }
    if (EQ(lhs, rhs)) { cnt++; continue; }
    if (n == 1) { continue; }
    cnt += solve(n-1, i, prod * i, rhs);
  }

  return cnt;
}

int main() {
  int n;
  while (cin >> p >> q >> a >> n, (p || q || a || n)) {
    lhs = (double)p / (double)q;
    cout << solve(n, 1, 1, 0) << endl;
  }

  return 0;
}