In the sequence 15,16,17,21,23,30,33,120, what comes next.?

Answer 1

These are ways to express 15 in different bases, starting with base 10 and descending.

15 written in base 10 --> 15
15 written in base 9 --> 16
15 written in base 8 --> 17
15 written in base 7 --> 21
15 written in base 6 --> 23
15 written in base 5 --> 30
15 written in base 4 --> 33
15 written in base 3 --> 120
15 written in base 2 --> 1111

So the next number in the sequence is 1111

Answer 2

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