The sequence given is a Fibonacci sequence, where each number is the sum of the two preceding numbers.
Starting with:
- 1
- 1 (1 + 0)
- 2 (1 + 1)
- 3 (1 + 2)
- 5 (2 + 3)
- 8 (3 + 5)
- 13 (5 + 8)
To find the next number in the sequence after 13:
- 8 + 13 = 21
Therefore, the next number in the sequence is 21.