input:1 output:4

input:2 output:7
input:3 output:10
input:4 output:13

What is the rule?

the rule is x3+1

Looks more like 3x+1

technically, since multiplication is commutative, x3 is the same as 3x, but you will find most people put the numeric coefficient first. . .

53

16564
21641
60
3
140.

2548

To find the rule that relates the given inputs and outputs, let's analyze the given examples:

Input: 1 → Output: 4
Input: 2 → Output: 7
Input: 3 → Output: 10
Input: 4 → Output: 13

As we look at the outputs, we see that they increase by 3 with each subsequent input. This indicates that there is a constant difference of 3 between the input and the output.

Hence, the rule can be defined as follows:
Subtract 1 from the input, and then multiply the result by 3 to get the output.

Using this rule, we can calculate the output for any given input.