Problems & Puzzles: Conjectures

Conjecture 80. Why 25?

In the Puzzle 900 Sebastián Martín Ruiz posed an question:

Why the numerator of the reduced quotient concerning to the product expression {Π[((pi)^2+1)/(pi-1)]} from i=1 to n, always end in "25" for n>2?

Emmanuel Vantieghem worked on this question and at the end he qualified it as a "conjecture" because he explained some cases, he failed to find a complete proof.

Q. Can you obtain a complete proof for the question-conjecture by Sebastian Martín Ruiz or find a counterexample?


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