ANSWERS: 3

could be any number.

6162017 Assuming this is an arithmetic sequence, the rule is "up three, down two," so the next number is 10. But we are not supposed to have to assume things in arithmetic.


Jewels VernExample: A magazine presented this sequence: 8,5,4,9,1,7,6,3,2 as a challenge to readers. After a suitable time they revealed that the digits were in alphabetic order. But a reader assumed it had to be mathematical and eventually sent an algorithm that generated that exact sequence!


10,13
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