Van der Waerden number $W(6,11)$

The smallest number $n$ such that if the integers $1$ to $n$ are colored with $6$ colors, there must be a monochromatic arithmetic progression of length $11$.

Lower bound: $419188538044$ (419,188,538,044)
Upper bound: Unknown

Verified bounds

Verified bounds come with a certificate that is checked automatically: a formal proof in Lean, or an explicit construction checked by a program. Submit a certificate.

Updates from the literature