I apologize if the motivation wasn't clear. At a mathematical level, it's a problem of multiplying N polynomials, each of which has two terms: 

For N=2:
(a+b)*(c+d) = ac + ad + bc + bd

For N=3:
(a+b)*(c+d)*(e+f) = ace + acf + ade + adf +
                  + bce + bcf + bde + bdf

[download]
What I was after was an explicit expression for each of the 2**N terms on the right-hand-side of these equations.

As for why one would want to do this beyond a homework question, this problem arises in theories of quantum computing, particularly in trying to write an arbitrary state in terms of what's called the computational basis for an N-qubit state.

In reply to Re^2: Obtaining terms in an expansion by randyk
in thread Obtaining terms in an expansion by randyk

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