What is the next number in the pattern 3, 5, 9, 17, ___?

Step-by-step solution

1. Observe the differences between consecutive numbers: $5-3=2$, $9-5=4$, $17-9=8$.
2. Notice that each difference doubles: $2,4,8$.
3. The next difference should be $8\times 2=16$.
4. Add this difference to the last term: $17+16=33$.

Concept tested: Sequence with doubling differences

Published 7 October 2026 · How this solution was prepared and checked