21 Metaprogramming library [meta]

21.2 Compile-time integer sequences [intseq]

21.2.2 Class template integer_­sequence [intseq.intseq]

namespace std { template<class T, T... I> struct integer_sequence { using value_type = T; static constexpr size_t size() noexcept { return sizeof...(I); } }; }
Mandates: T is an integer type.