Ahlan wa Sahlan.
Excuse me ... .
We can seem guess the next terms in the sequence, say, $1,2,3,4,5,\cdots$ ... .
Maybe, we will say that the next terms is $6,7,8,9,10,\cdots$ ... .
But, in fact, in real line, we cannot guess the next term, because the next terms is not unique ... .
Really, the next term is undeterminated ... .
We can make various patterns by the method, called interpolation ... .
...
Let, the sequence $u_1,\dots,u_j,\dots\in\mathbb{R}$ ... .
We are asked to guess the next terms ... .
The interpolation is such that :
\[ u_n=f(a_1,\dots,a_j,n) \]
where :
$f$ is fixed function,
$a_1,\dots,a_j\in\mathbb{R}$ are unknown constant ... .
In this method, we must substitute the sequence to the pattern of interpolation ... , and ... find all $a_1,\dots,a_j$ ... .
If we are given the pattern of the sequence, however, we can guess the next terms ... .
Thank you very much for the attention ... .

Sanctus, Sanctus, Dominus Deus Sabaoth.