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Math Help - Combinations problem

  1. #1
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    Combinations problem

    I've been challenged to come up with the total possible number of combinations for a given set of ingredients. For the purposes of this challenge, AB == BA. In other words, given ingredients 'A', 'B', and 'C', the possible combinations are as follows:

    A, B, C, AB, AC, BC, ABC

    BA,CA,CB,ACB,BAC,BCA,CAB, and CBA are not counted because for our purposes order is irrelevant. Also, each item may only be used once. It's been a LONG time since I got out of school, but I can't think of an equation that satisfies this set of rules. Am I missing something obvious? Is there a more complex formula that is required? Any assistance would be greatly appreciated.
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  2. #2
    MHF Contributor
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    Re: Combinations problem

    The number of nonempty subsets of a set with n elements is 2^n-1 (see Wikipedia).
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