MathCastle
AIMEChallengeAdvanced Number Theory

Advanced Number Theory · Challenge problem

Find the number of integers nn with 1≤n≤30001 \le n \le 3000 such that n≡5(mod11)n \equiv 5 \pmod{11} and gcd⁡(n,12)=1\gcd(n, 12) = 1.