Let *S* = {1,5,9,13,...} = {4*k*+1 | *k* is a non-negative integer}.
We will call an element of *S* an *S*-prime if it cannot be written as
the product of two smaller numbers in *S*.

Find an element of *S* that can be written as a product of *S*-primes
in two essentially different ways (i.e. changing the order of the *S*-primes
does not count).

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The solution will be posted shortly.
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