Ramsey number $R(9,13)$
The smallest number $n$ such that any two-coloring of the edges of the complete graph $K_n$ must contain either a monochromatic $K_{9}$ in the first color or a monochromatic $K_{13}$ in the second color.
Lower bound:
Unknown
Upper bound:
$64864$
(64,864)
Updates
-
2007
Upper bound: $64864$
(64,864)
Huang Yi Ru, Wang Yuandi, Sheng Wancheng, Yang Jiansheng, Zhang Ke Min and Huang Jian, New Upper Bound Formulas with Parameters for Ramsey Numbers, Discrete Mathematics, 307 (2007) 760-763.
[via Small Ramsey Numbers, Stanisław Radziszowski, 2024-09-06]