The q-tangent continued-fraction conjecture for parameter tuple (1,0,1,0)(1,0,1,0)

From papers

Let qq be a parameter and let tanq(z)\tan_q(z) denote the q-tangent function. For the parameter tuple (A,B,C,D)=(1,0,1,0)(A,B,C,D)=(1,0,1,0), consider the continued fraction

tanq(z)=z[1]qq0z2[3]qq2z2[5]qq1z2[7]qq9z2.\tan_q(z)=\cfrac{z}{[1]_q q^{0}-\cfrac{z^2}{[3]_q q^{-2}-\cfrac{z^2}{[5]_q q^{1}-\cfrac{z^2}{[7]_q q^{-9}-\cfrac{z^2}{\ddots}}}}}.

Continued-fraction conjecture. The positive powers of qq in this continued fraction follow the sequence 0,1,6,15,0,1,6,15,\dots, given by k(2k1)k(2k-1), while the negative powers follow 2,9,20,35,2,9,20,35,\dots, given by (k+1)(2k1)(k+1)(2k-1).

This conjecture proposes an explicit continued-fraction pattern for the q-tangent function in the indicated parameter case. The associated continuant polynomials are not known: the source states that the coefficients cannot presently be guessed and leaves their expansion as an open problem.

Progress summary

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Sources & referencesView supporting material

Primary source

Helmut Prodinger, “Combinatorics of geometrically distributed random variables: New q-tangent and q-secant numbers”, arXiv:math/9910096 (1999).

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