Abstract
In this paper, we prove some congruences conjectured by Z.-W. Sun: For any prime \(p>3\), we determine
modulo \(p^2\), where \(C_k=\frac{1}{k+1}\left( {\begin{array}{c}2k\\ k\end{array}}\right) \) is the k-th Catalan number and \(C_k^{(2)}=\frac{1}{2k+1}\left( {\begin{array}{c}3k\\ k\end{array}}\right) \) is the second-order Catalan numbers of the first kind. And we prove that
where \(D_n=\sum _{k=0}^{n}\left( {\begin{array}{c}n\\ k\end{array}}\right) \left( {\begin{array}{c}n+k\\ k\end{array}}\right) \) is the n-th Delannoy number and \(q_p(2)=(2^{{p-1}}-1)/p\) is the Fermat quotient.
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Acknowledgements
The author would like to thank Prof. Z.-W. Sun for some of his helpful comments. He also thanks the referee for valuable suggestions.
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This research was supported by the Natural Science Foundation (Grant No. 11571162) of China.
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Mao, GS. On sums of binomial coefficients involving Catalan and Delannoy numbers modulo \(p^2\) . Ramanujan J 45, 319–330 (2018). https://doi.org/10.1007/s11139-016-9853-6
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DOI: https://doi.org/10.1007/s11139-016-9853-6