Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: $\pi$-Formulae from Dual Series of the Dougall Theorem   By means of the extended Gould-Hsu inverse series relations, we find that the
dual relation of Dougall's summation theorem for the well--poised
$_7F_6$-series can be utilized to construct numerous interesting
Ramanujan--like infinite series expressions for $\pi^{\pm1}$ and $\pi^{\pm2}$,
including an elegant formula of $\pi^{-2}$ due to Guillera.

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The categories of this paper are: hep-th
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The categories of this paper are: stat
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The categories of this paper are: nucl-th
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The categories of this paper are: q-bio
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The categories of this paper are: cmp-lg
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The categories of this paper are: gr-qc
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The categories of this paper are: astro-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: eess
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The categories of this paper are: adap-org
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The categories of this paper are: math-ph
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The categories of this paper are: nlin
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The categories of this paper are: bayes-an