>>35
(引用開始)
>0.9<0.99<0.999<・・<9/10^n<・・<1
これが＜列であるための必要条件は、どの＜についてもその左右が定まっていること。分かる？　〇＜△の〇と△が定まっていなければ＜列ではありません。分かる？
(引用終り)

下記英文をば
英語では
Sequence、列
infiniteで
”a singly infinite sequence or a one-sided infinite sequence”
と
”doubly infinite sequence”、”bi-infinite”
とあるよ

まあ、低レベルでは理解難しいよな
無理するな

https://en.wikipedia.org/wiki/Sequence
Sequence

Finite and infinite
The length of a sequence is defined as the number of terms in the sequence.

Normally, the term infinite sequence refers to a sequence that is infinite in one direction, and finite in the other-the sequence has a first element, but no final element.
Such a sequence is called a singly infinite sequence or a one-sided infinite sequence when disambiguation is necessary.
In contrast, a sequence that is infinite in both directions-i.e. that has neither a first nor a final element-is called a bi-infinite sequence, two-way infinite sequence, or doubly infinite sequence.
A function from the set Z of all integers into a set, such as for instance the sequence of all even integers ( ..., -4, -2, 0, 2, 4, 6, 8, ... ), is bi-infinite.
This sequence could be denoted {\displaystyle (2n)_{n=-∞〜 ∞}.