How 'believe in yourself' message helped Claude take on 167-year-old maths problem?

An unreleased version of Anthropic's Claude took on the 167-year-old Riemann Hypothesis after an employee sent messages like "believe in yourself" and "keep going". This seemingly helped Claude overcome initial scepticism. After trying 650 ideas, Claude coordinated 60 subagents and ran thousands of checks, improving the known lower bound for zeros satisfying the hypothesis from 41.6% to 67.2%.