#include <stdio.h>

double f(int i, int n){
    if(i==n)
        return 1 + i/(2.0*i+1)*1.5;
    else
        return 1 + i/(2.0*i+1)*f(i+1, n);
}

double newton_series (int n){
    return 2.0*f(1, n);
}

int main() {
    int i, j;
    for(i = 1; i < 20; i++) {
        printf("%d:%fn", i, newton_series(i));
    }
    return 0;
}