#include<bits/stdc++.h>
using namespace std;

#define fr first
#define sc second
#define pb push_back
#define mp make_pair

typedef long long ll;
typedef pair<int, int> pii;

inline ll rd() {
	ll x = 0;
	bool f = 0;
	char c = getchar();
	for (; !isdigit(c); c = getchar()) f |= (c == '-');
	for (; isdigit(c); c = getchar()) x = x * 10 + (c ^ 48);
	return f ? -x : x;
}

double fpow(double x, int t) {
	double res = 1.0;
	for (; t; t >>= 1, x = x * x)
		if (t & 1) res = res * x;
	return res;
}

#define N 1000007

double f[N];

int main() {
	int n = rd(), p = rd(), k = rd();
	for (int i = 1; i <= n + 1; ++i) 
		f[i] = fpow(1.0 * (i - 1) / n, k);
	double ans = p * f[p];
	for (int i = p; i <= n; ++i) ans += (i + 1) * 0.5 * (f[i + 1] - f[i]);
	printf("%.10lf\n", ans);
	return 0;
}