English: Animation that visualizes the "Sieve of Sundaram" algorithm.
The Sieve of Sundaram is an algorithm for finding all prime numbers up to a specified integer. One starts with a list of integers 1 to n. From the list, numbers of the form i + j + 2ij where 1 <= i <= j and i + j + 2ij <= n are removed. The remaining numbers in the list are then doubled and incremented by one.
Various optimizations of the algorithm exist, but this visualization shows the verbatim, unoptimized implementation.
This visualization is inspired by Sebastian Koppehel's visualization of the Sieve of Eratosthenes (link).