Study Materials Number Theory Notes Tutorials Mathematics For TopCoders Number Theory : HackerEarth Eulers Toitent Function : GeeksForGeeks Eulers Toitent : HackerEarth Sieve of Eratosthenes Segmented Sieve Self Read Questions Codeforces: Almost Prime Codeforces: T-primes Spoj: PRIME1 - Prime Generator Codechef: Count K-Primes Codechef: Primality Test Spoj: PRIME1 - Prime Generator (Segmented Sieve) Spoj: ALICESIE - Alice Sieve Spoj: ETF - Euler Totient Function Spoj: ETFS - Euler Totient Function Sieve HackerEarth: Chandu and his Interns