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Convergence and analytic continuation for a class of regular C-fractions. (English) Zbl 0553.30004

Regular C-fractions \(f(\alpha)\equiv 1+\frac{a_ 1\alpha}{1+}\frac{a_ 2\alpha}{1+}..\). with \(a_ n=an^ 2+bn+c+V_ n,\) \(| V_ n|\) sufficiently small are examined. In the case \(V_ n=0\), exact expressions are obtained which reveal a two-sheeted Riemann structure for f(\(\alpha)\). If \(V_ n\neq 0\) analytic properties are obtained by means of perturbation theory applied to the associated difference equation. A conjecture that f(\(\alpha)\) is the ratio of entire functions of 1/\(\sqrt{\alpha}\) for an even larger class of C-fractions is proved for the case \(a_ n=\prod^{N}_{i=1}(n+r_ i)^{p_ i},\) \(r_ i>-1,\) \(\sum^{N}_{i=1}p_ i=2.\)

MSC:

30B70 Continued fractions; complex-analytic aspects
40D15 Convergence factors and summability factors
39A10 Additive difference equations
33C05 Classical hypergeometric functions, \({}_2F_1\)

Keywords:

C-fractions
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