Perfect! Thanks much, Charles. BTW, Aubry ends the paper I cited with the famous (in some circles) ... The use of this book is quite large, my dear friend No matter how modest it looks, You study it carefully and find that it gives As much as a thousand big books.

Not quite. What I'd like is a citation for the equivalence that Franel uses in "Les suites...".

It is this equivalence that Franel uses in connecting Farey and Riemann.

Thanks much, John. Another historical tidbit about Franel is that he presented the very first paper at the very first International Congress of Mathematicians. The congress was held in Zurich in 1897. The opening lecture was to be given by Poincare who was ill and couldn't attend. Franel was called upon to read Poincare's paper. Talk about being thrown into the deep end of the pool! Cheers, Scott