Multiple choice

Find the wrong term in the following number series: 1, 5, 13, 31, 61, 125, 253

  1. 1

  2. 5

  3. 31

  4. 61

  5. 125
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C Correct answer
AI explanation

Calculate the differences between consecutive terms: 4, 8, 18, 30, 64, 128. The pattern of differences should be doubling each time (4, 8, 16, 32, 64, 128). Because 61 + 32 = 93 (not 125), the sequence diverges at that point; 31 is the wrong term and should be 63.

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