Template specialization in case of variadic template function

I have this function that is a a variadic template function:

template<uint C>
double foo(){
    double cpt = 1;
    for(uint i=0; i<10; i++){
        cpt += i*C; 
    }
    return cpt;
}

template<uint C1, uint C2, uint... CCs>
double foo(){
    double cpt = 1;
    for(uint i=0; i<10; i++){
        cpt += i*C1;    
    }
    return cpt + foo<C2, CCs...>();
}

And it works perfectly as expected but I think it is not the correct way to do what I want to do. I tried to write something like that:

double foo(){
    return 0;
}

template<uint C1, uint... CCs>
double foo(){
    double cpt = 1;
    for(uint i=0; i<10; i++){
        cpt += i*C1;    
    }
    return cpt + f<CCs...>();
}

But I have the error no matching function for call foo() note: couldn't deduce template parameter C1. I also tried with a template <typename T> on top of the first foo function but I have the same error.

Does someone know why ? I am using g++ 5.4 with -std=c++11 and -O3 flags.