/* compute zeta(k) */

#include <stdio.h>

int
main(int argc, char **argv)
{
	int i, j, k, q = 0;
	double t = 0;

	if (argc < 2) {
		fprintf(stderr,
			"usage: zetacalc k [offset] (k an integer >= 2)\n");
		return 1;
	}
	k = atoi(argv[1]);
	if (argc > 2)
		q = atoi(argv[2]);

	for (i = 1; i < 1000000; ++i) {
		double r = 1.0;
		for (j = 0; j < k; ++j)
			r *= i;
		r += q;
		t += 1 / r;
	}

	printf("%lf\n", t);
	return 0;
}