#include <iostream>
#include <vector>
#include <cmath>
#include <iomanip>
#include <algorithm>
using namespace std;

// 有理数
long long calc_gcd(long long a, long long b) {return b ? calc_gcd(b, a % b) : a;}
struct frac {
    long long first, second;

    using D = long double;
    inline frac normalize() {
        if (second < 0) {first = -first; second = -second;}
        //long long d = calc_gcd(first, second);
        //if (d == 0) {first = 0; second = 1;}
        //else {first /= d; second /= d;}
        return *this;
    }
    frac(long long f = 0, long long s = 1) : first(f), second(s) { normalize(); }
    inline D to_d() const { return D(first) / second; }
    inline frac operator - () { (*this).first *= -1; return (*this); }
    inline const frac& operator = (long long a) { *this = frac(a, 1); return *this; }
    inline const frac& operator += (const frac& a);
    inline const frac& operator += (long long a);
    inline const frac& operator -= (const frac& a);
    inline const frac& operator -= (long long a);
    inline const frac& operator *= (const frac& a);
    inline const frac& operator *= (long long a);
    inline const frac& operator /= (const frac& a);
    inline const frac& operator /= (long long a);
    inline friend ostream& operator << (ostream& s, const frac& f) { 
        s << f.first; if (f.second != 1) s << "/" << f.second; return s;
    }
};
inline bool operator == (const frac &a, const frac&b) {
    return a.first * b.second == a.second * b.first;
}
inline bool operator != (const frac &a, const frac &b) { return !(a == b); }
inline bool operator < (const frac& a, const frac& b) {
    return a.first * b.second < a.second * b.first;
}
inline bool operator > (const frac& a, const frac& b) { return b < a; }
inline bool operator <= (const frac& a, const frac& b) {
    return a.first * b.second <= a.second * b.first;
}
inline bool operator >= (const frac& a, const frac& b) { return b <= a; }
inline frac operator + (const frac& a, const frac& b) {
    frac res;
    res.first = a.first * b.second + a.second * b.first;
    res.second = a.second * b.second;
    res.normalize();
    return res;
}
inline frac operator - (const frac& a, const frac& b) {
    frac res;
    res.first = a.first * b.second - a.second * b.first;
    res.second = a.second * b.second;
    res.normalize();
    return res;
}
inline frac operator * (const frac& a, const frac& b) {
    frac res;
    res.first = a.first * b.first;
    res.second = a.second * b.second;
    res.normalize();
    return res;
}
inline frac operator / (const frac& a, const frac& b) {
    frac res;
    res.first = a.first * b.second;
    res.second = a.second * b.first;
    res.normalize();
    return res;
}
inline frac abs(const frac& a) {
    frac res; res = a; res.normalize(); 
    if (res.first < 0) res.first = res.first * (-1);
    return res;
}
inline const frac& frac::operator += (const frac& x) {*this = *this + x; return *this;}
inline const frac& frac::operator += (long long x) {*this = *this + x; return *this;}
inline const frac& frac::operator -= (const frac& x) {*this = *this - x; return *this;}
inline const frac& frac::operator -= (long long x) {*this = *this + x; return *this;}
inline const frac& frac::operator *= (const frac& x) {*this = *this * x; return *this;}
inline const frac& frac::operator *= (long long x) {*this = *this * x; return *this;}
inline const frac& frac::operator /= (const frac& x) {*this = *this / x; return *this;}
inline const frac& frac::operator /= (long long x) {*this = *this / x; return *this;}



int p, q, a, n;
int rec(frac f, int con, int bunbomax, int mul) {
    if (con == 0) { // 残り 0 回だったら f = 0 じゃなきゃダメ
        if (f == 0) return 1;
        else return 0;
    }
    if (f == 0) return 1; // 0 になったら終わり

    int res = 0;
    for (int i = a/mul; i >= bunbomax; --i) {
        if (f < frac(1, i)) break;
        res += rec(f - frac(1, i), con - 1, i, mul * i);
    }
    return res;
}


int main() {
    while (cin >> p >> q >> a >> n, n) {
        frac start(p, q);
        int res = rec(start, n, 1, 1);
        cout << res << endl;
    }
}



Measured memory_bytes: 3084