+ else {
+ /* Yes! We've found that %$a = a'^p$% for some %$a'$%. We know
+ * (induction) that %$a'$% is not a perfect %$q$%th power for any prime
+ * %$q < p$%, so we can write %$a = x^n$% if and only if we can write
+ * %$a' = x'^{n'}$%, in which case we have %$a = a'^p = x'^{p n'}$%.
+ */