The is amultiplicative functionso that if m and n arecoprime, then...

(1)

For and is and is anevennumber, so that the solutions of the equation...

(2)

... are obtained by systematic search of couples of coprime numbers m and n for which is...

(3)

Since solutions are...

Since also solutions are...

Finally is so that solution is...

The numbers k for which is are...

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