Infinitely many Catalan numbers with proportional 2- and 3-adic valuations

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Let Cn=1n+1(2nn)C_n=\frac{1}{n+1}\binom{2n}{n} denote the nnth Catalan number, and let νp(m)\nu_p(m) be the exponent of the prime pp in the prime factorization of mm. Assume that a,b≥1a,b\geq 1 are integers. Catalan valuation conjecture. There exist infinitely many positive integers nn such that

aν2(Cn)=bν3(Cn).a\nu_2\bigl(C_n\bigr)=b\nu_3\bigl(C_n\bigr).

This is a related question about the 2- and 3-adic valuations of Catalan numbers, analogous to the paper's results on collisions between binary and ternary digit sums. The source leaves this as another open problem.

References

Primary source

Michael Drmota and Lukas Spiegelhofer, “The joint distribution of binary and ternary digits sums”, arXiv:2501.00850 (2025).

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