Find the missing term:
3, 7, 15, 31, ?

Question

Accepted Answer

1. Check the differences: 7-3=4, 15-7=8, 31-15=16.

2. Differences double each time (4, 8, 16). So next difference = 32.

3. Add to the last term: $31+32=63$.

4. Another view: numbers are $2^2-1,2^3-1,2^4-1,2^5-1$, so next is $2^6-1=63$.

FINAL_ANSWER: b

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Answer

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