ntuple.cpp

#include <iostream>
#include <tuple>

template<unsigned, typename...>
struct ntuple_impl;

template<unsigned N, typename E, typename... Es>
struct ntuple_impl<N, std::enable_if_t<(N > 1)>, E, Es...>
{
    using type = typename ntuple_impl<N - 1, void, E, E, Es...>::type;
};

template<typename... Es>
struct ntuple_impl<1, void, Es...>
{
    using type = std::tuple<Es...>;
};

template<unsigned N, typename T>
using ntuple = ntuple_impl<N, void, T>;

template<unsigned N, typename T>
using ntuple_t = typename ntuple<N, T>::type;

int main() {
    auto t = ntuple_t<3, int>{};
    static_assert(std::is_same_v<decltype(t), std::tuple<int, int, int>>);
    return 0;
}