Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A skeleton model to enumerate standard puzzle sequences   Guo-Niu Han [arXiv:2006.14070 [math.CO]] has introduced a new combinatorial
object named standard puzzle. We use digraphs to show the relations between
numbers in standard puzzles and propose a skeleton model. By this model, we
solve the enumeration problem of over fifty thousand standard puzzle sequences.
Most of them can be represented by classical numbers, such as Catalan numbers,
double factorials, Secant numbers and so on. Also, we prove several identities
in standard puzzle sequences.

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The categories of this paper are: adap-org
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The categories of this paper are: q-fin
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The categories of this paper are: plasm-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: hep-th
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The categories of this paper are: math-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: cs
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The categories of this paper are: nucl-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: funct-an
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The categories of this paper are: supr-con
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The categories of this paper are: quant-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
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The categories of this paper are: q-bio