MathCastle
AIMEChallengeAdvanced Number Theory

Advanced Number Theory · Challenge problem

Find the number of integers nn with 1≤n≤20251 \le n \le 2025 such that n≡3(mod7)n \equiv 3 \pmod{7} and gcd⁡(n,8)=1\gcd(n, 8) = 1.