### Theory:

We have seen iterative processes in real life. It also can be seen in number sequences.
A number sequence is obtained by doing repetitive operation. It may increase or decrease during the process.
Let's see some examples of number sequences.
Example:
1. Add $$4$$ with the starting number $$3$$, you will get the number $$7$$. Now add $$4$$ with the resultant $$7$$, you will get the number $$11$$, again add $$4$$ with the new resulting $$11$$, this process goes on.

Here, adding $$4$$ is the iterative process.

$$3 + 4$$, $$7 + 4$$, $$11 + 4$$, $$15 + 4$$, …

The sequence obtained is $$3$$, $$7$$, $$11$$, $$16$$, …

2. Subtract $$3$$ from the starting number $$99$$, you will get the number $$96$$. Now subtract $$3$$ from the resultant $$96$$, you will get the number $$93$$, again subtract $$3$$ from the new resulting $$93$$, this process goes on.

Here, subtracting $$3$$ is the iterative process.

$$99 - 3$$, $$96 - 3$$, $$93 - 3$$, $$90 - 3$$, …

The sequence obtained is $$99$$, $$96$$, $$93$$, $$90$$, …

3. Multiply the starting number $$1$$ by $$4$$, you will get the number $$4$$. Now multiply the resultant $$4$$ by $$4$$, you will get the number $$16$$. Multiply the new resulting $$16$$ by $$4$$; this process goes on.

Here, multiplying $$4$$ is the iterative process.

$$1 \times 4$$, $$4 \times 4$$, $$16 \times 4$$, $$64 \times 4$$…

The sequence obtained is $$4$$, $$16$$, $$64$$, $$256$$, …

4. $$5$$, $$50$$, $$500$$, …

In this pattern, the values get increased when the number of zeroes increased.

5. $$3$$, $$9$$, $$27$$, $$81$$, …

This pattern is obtained by generating $$3 \times 3^0$$, $$3 \times 3^1$$, $$3 \times 3^2$$, $$3 \times 3^3$$…

6. $$1$$, $$11$$, $$111$$, $$1111$$, …

In this pattern, the values get increased when the number of ones increased.