Find the number of partitions of into two sets such that none of the sets contains two distinct elements whose sum is a power of .
Solution
**The answer is .**
Let us call a partition of into two sets *nice partition for *, if none of the sets contains two distinct elements whose sum is a power of . Let be the number of nice partitions for . We observe that removing from a nice partition for gives a nice partition for . Therefore, we can obtain the nice partitions for by adding to the nice partitions for .
If for some positive integer , then as and , we must add into the set not containing . Therefore, .
If for some positive integer , then since , we can add into any of the sets and hence .
As and , we conclude that .
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