## Weekly challenge 153

Two relatively straight forward tasks this week. Solutions are in Python only as a result.

## TASK #1 › Left Factorials

### Task

Write a script to compute Left Factorials of 1 to 10. Please refer OEIS A003422 for more information.

### My solution

So after reading the linked OEIS page, I was really confused. However we can look at the solution to find a straight forward pattern, the difference between the digits is the factorials, that is `S(n) = S(n-1) + (n-1)!`

. The OEIS list starts the list at 0, but the expected output starts at 1.

### Example

```
$ ./ch-1.py
1, 2, 4, 10, 34, 154, 874, 5914, 46234, 409114
```

## TASK #2 › Factorions

### Task

You are given an integer `$n`

.

Write a script to figure out if the given integer is factorion. A factorion is a natural number that equals the sum of the factorials of its digits.

## My solution

For this task, we start with `n`

as a string. I then use `num`

as the integer representation, checking that the value is not a negative. Then it is a matter of using `sum(math.factorial(int(x)) for x in n)`

to compute the sum of all factorials of the digits/ Finally compare that figure with `num`

and print `1`

if they are the same or `0`

otherwise.

### Examples

```
$ ./ch-2.py 145
1
$ ./ch-2.py 123
0
```

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