Wrong term in a series of n squared + 1

The same question, asked 2 times: 15 Sep 2025 S1*, 18 Sep 2025 S2. Every wording below, oldest first.

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Question 1
15 Sep 2025 S1
13 $Which term is wrong in the series : 2, 5, 10, 17, 26, 36$
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Question 2
18 Sep 2025 S2
6 $Find the WRONG term in the given series. 5, 10, 15, 26, 37, 50$
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