Probability

# Recursion Warmup

What is the next number in this sequence? (There are no hidden cubes.)

$0, 1, 3, 6, 10, 15...$

How many corners does a hypercube (a 4-dimensional cube) have?

How many line-segments are there in the 4th image of this growing tree sequence?

What is the sum of the first 13 positive odd numbers?

The sizes of the first 9 squares that make this spiral are:

$1, 1, 2, 3, 5, 8, 13, 21, 34...$

How big is the 10th square added to the spiral?

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