Summary of Sequences

In class today I we went over the Sequences chapter.

You can see a recording of the class here

Here is the notebook I used in class: sequences.ipynb

We started with the quiz which was won by Vincent

• Daf: 2 wins
• Anthony: 1 win
• Ben: 1 win
• Joe: 1 win
• Millie: 1 win
• Tom: 1 win
• Vincent: 1 win

During the quiz we spent some time looking at this function which is defined recursively:

def get_sequence(n):
    """
    ...
    """
    if n == 4:
        return 1
    if n in [1, 2, 3]:
        return n
    return get_sequence(n - 2) + get_sequence(n - 1)

During the discussion about what get_sequence(n=7) gives I drew the following on the board:

If we work back from the end points of that image we get:

• get_sequence(n=3)=3
• get_sequence(n=4)=1

Which in turn gives:

• get_sequence(n=5)=get_sequence(n=3) + get_sequence(n=4) = 3 + 1 = 4

Which in turn gives:

• get_sequence(n=6)=get_sequence(n=4) + get_sequence(n=5) = 4 + 1 = 5

Which in turn gives:

• get_sequence(n=7)=get_sequence(n=5) + get_sequence(n=6) = 5 + 4 = 9