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

From papers

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,b1a,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.

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Sources & referencesView supporting material

Primary source

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

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