Answer: What Comes Next? #402

The answer is A: 26.

The finished pattern: 2, 2, 4, 6, 10, 16, 26.
The finished pattern.

The rule

Each number is the two numbers before it added together. 2 + 2 = 4, 2 + 4 = 6, and so on. The famous Fibonacci sequence works like this, starting 1, 1, 2, 3, 5, 8.

The pattern as Python code

Here is a tiny Python program that follows the same rule. Type it into IDLE and run it to print the whole pattern, including the answer.

a, b = 2, 2
for step in range(7):
    print(a)
    a, b = b, a + b

When you run it, Python prints:

2
2
4
6
10
16
26

Pixel says: Try changing a number in the code and run it again. Can you make the pattern go on for 20 steps? Meow!