1. Prime numbers
   1. Euclid (infinitude of prime numbers)
   2. prime number theorem
   3. Riemann hypothesis
   4. prime ideals
   5. Mersenne primes
   6. public-key cryptography
   7. perfect numbers
2. Fibonacci numbers
   1. The simplest properties
   2. Theoretic properties
   3. continued fractions
   4. search theory
3. Egyptian numerals
4. Pi 3.1415926