How to have a static constexpr array in a struct

Question

So I want to have a struct like this:

struct A {
    static constexpr int arr[10] = {
        1, 2, 3, 4, 5, 6, 7, 8, 9, 10
    };
};

In which I have a static constexpr array. If I try to access this array for example with this function:

int main(){
    for (int i = 0; i < 10; i++){
        printf("%i ", A::arr[i]);
    }
}

It says I have an undefined reference to 'A::arr'. How am I supposed to access this array?

I have tried using a getter function in the class like:

static constexpr int get(int index){
    return arr[index];
}

I also tried declaring an instance of the class, and accessing it through that:

A a;
printf("%i", a.arr[0]);