EDB — 16G

[16G] Given nonempty sets \(I,A\), a sequence with indexes in \(I\) and taking values in \(A\) is a function \(a:I→ A\); this though is usually written by the notation \(( a_ n )_{ n ∈ I}\) . To denote the codomain, the notation \( ( a_ n )_{ n ∈ I}⊆ A\) is also employed. In this text, in most cases, we will have that \(I=ℕ\), and in this case we will simply write \((a_{n})\).