F. M. S. Lima

  1. An infinite discrete set of counterexamples to a "theorem" by Gun and co-workers and its correct reformulation.

    Authors: F. M. S. Lima
    Subjects: Number Theory
    Abstract

    In a recent work [JNT \textbf{129}, 2154 (2009)], Gun, Murty and Rath (GMR)
    have introduced a "theorem" asserting that the series
    $\sum_{n=-\infty}^{\infty}{1/(n+\alpha)^k} $ yields a transcendental number for
    all $ \alpha \in \mathbb{Q} \backslash \mathbb{Z} $, $k$ being an integer
    greater than 1. I show here in this short paper that this conjecture is
    \emph{false} whenever $\alpha$ is a half-integer and $k$ is odd. I also prove
    that this infinite discrete set comprises all possible counterexamples to the
    GMR conjecture, which allows for its correct reformulation.

  2. An Euler-type formula for the Dirichlet beta function at even values and an exact closed-form expression for a class of rational zeta series.

    Authors: F. M. S. Lima
    Subjects: Number Theory
    Abstract

    In a recent work [JNT \textbf{118}, 192 (2006)], Dancs and He found an
    Euler-type formula for $ \zeta{(2 n+1)}$, $ n $ being a positive integer, which
    contains an alternating series that seems not to be reducible to a finite
    closed-form. This certainly reflects a greater complexity in comparison to
    $\zeta(2n)$, which is a rational multiple of $\pi^{2n}$ according to a
    well-known formula by Euler. For the Dirichlet beta function, the things are
    "inverse": $\beta(2n+1)$ is a rational multiple of $\pi^{2n+1}$, whereas no
    closed-form expression is known for the numbers $\beta(2n)$.

  3. A simple approximate expression for the Ap\'ery's constant accurate to 21 digits.

    Authors: F. M. S. Lima
    Subjects: Number Theory
    Abstract

    I present here a simple approximate expression for $\zeta{(3)}$, the
    Ap\'ery's constant, which is accurate to 21 digits. This closed-form expression
    has been found experimentally via the PSLQ algorithm, with a search basis
    composed by some suitable real numbers involving $ \pi$, $ \ln{2} $, $
    \ln{(1+\sqrt{2})}$, and $G$ (the Catalan's constant). The very simple
    \emph{Maple} code written for finding the rational coefficients of this
    expression is also shown.

  4. Using known zeta-series to elucidate the origin of the Dancs' series for $ \ln{2} $ and the odd zeta-values.

    Authors: F. M. S. Lima
    Subjects: History and Overview
    Abstract

    In a recent work [JNT \textbf{118}, 192 (2006)], Dancs and He have found new
    "Euler-type" formulas for $ \ln{2} $ and $ \zeta{(2 n+1)}$, $ n $ being a
    positive integer, each containing a series that apparently can not be evaluated
    in closed form, providing some insight into why the odd case is more difficult
    than the even, for which the Euler's formula applies, showing that $ \zeta{(2
    n)} $ is a rational multiple of $\pi^{2 n}$.

  5. A shortcut for evaluating some definite integrals of "log-trig" functions from products and limits.

    Authors: F. M. S. Lima
    Subjects: History and Overview
    Abstract

    In this short paper, I introduce a simple method for exactly evaluating the
    definite integrals $\int_0^{\pi}{\ln{(\sin{\theta})} d\theta}$,
    $\int_0^{\pi/2}{\ln{(\sin{\theta})} d\theta}$,
    $\int_0^{\pi/2}{\ln{(\cos{\theta})} d\theta}$, and
    $\int_0^{\pi/2}{\ln{(\tan{\theta})} d\theta}$ in finite terms. The method
    consists in taking into account certain products of trigonometric functions at
    rational multiples of $\pi$ whose logarithm yields sums that can be promptly
    written in the form of Riemann sums, and then to take the limit as the number
    of terms tends to infinity.

  6. On the possible exceptions for the transcendence of the log-gamma function at rational values and its consequences for the transcendence of $ \log{\pi} $ and $ \pi e $.

    Authors: F. M. S. Lima
    Subjects: Number Theory
    Abstract

    In a recent work published in this journal [JNT \textbf{129}, 2154 (2009)],
    it has been argued that the numbers $\log{\Gamma(x)} + \log{\Gamma(1-x)}$, $x$
    being a rational number between 0 and 1, are transcendental with at most
    \emph{one} possible exception, but the proof presented there is
    \emph{incorrect}. Here in this paper, I point out the mistake committed in that
    proof and I present a theorem that establishes the transcendence of those
    numbers, with at most \emph{two} possible exceptions.

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