We define the sequence ```SF``` in the following way in terms of four previous sequences: ```S1```, ```S2```, ```S3``` and ```ST```
We are interested in collecting the terms of SF that are multiple of ten.
The first term multiple of ten of this sequence is  ```60```
Make the function ```find_mult10_SF()``` that you introduce the ordinal number of a term multiple of 10 of SF and gives us the value of this term.
Let's see some cases: 
```python
find_mult10_SF(1) == 60
find_mult10_SF(2) == 70080
find_mult10_SF(3) ==  90700800
```
``` haskell
findMult10SF 1 `shouldBe` 60
findMult10SF 2 `shouldBe` 70080
findMult10SF 3 `shouldBe` 90700800
```
Memoization is advisable to have a more agile code for tests.
Your code will be tested up to the 300-th term, multiple of 10.
Happy coding!!
def find_mult10_SF(n):
    return 16**n * (81**n + 9) // 24
def find_mult10_SF(n):
    return 16**n * (81**n + 9) // 24