Sang-hyun Kim

collaborators

2 papers

math.NT2026

Irrationality of rapidly converging series: a problem of ErdÅs and Graham

Kevin Barreto, Jiwon Kang, Sang-hyun Kim +2

Answering a question of ErdÅs and Graham, we show that the double exponential growth condition $lim sup_{n \to \infty} a_{n}^{1/ I ¨ ^{n}} = \infty$ for a strictly increasing sequence of posi…

math.NT2026

Optimal Farey sequence for the Congruence subgroup $I^_{0} (2^{n})$

Nhat Minh Doan, Sang-hyun Kim, Mong Lung Lang +1

We prove that $I^_{0} (2^{n})$ ( $n \geq 2$ ) has a Farey sequence ${e_{i}}$ such that $e_{i} \leq 2^{n - 1}$ for all $e_{i}$ . The above upper bound is optimal, and there exists a unique $j$ such t…

Irrationality of rapidly converging series: a problem of ErdÅs and Graham

Optimal Farey sequence for the Congruence subgroup I^0​(2n)

Irrationality of rapidly converging series: a problem of ErdÅs and Graham

Optimal Farey sequence for the Congruence subgroup $I^_{0} (2^{n})$