# Visualization of Eratosthenes’ sieve

In otherwise great paper on prime numbers, I found following visualization of Eratosthenes’ sieve:

I found it somewhat scary and confusing.

Is there any better visualization of Eratosthenes’ sieve out there?

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Try to find an animation. A fixed image is terrible for representing an algorithm. – Thomas Andrews Jul 20 '14 at 21:22
A nice feature of this visualization is that it shows the pattern of multiples of each prime--including numbers that are multiples of more than one prime. You don't get the full effect of this when each number has to be marked in just one way, even if you use a different color for each prime. But it does result in a very cluttered diagram. – David K Jul 20 '14 at 21:33
All primes except for $2$ and $3$ are of the form $6n\pm1$. Hence the $2\times2=4$ columns in the table of width $12$. – Lucian Jul 20 '14 at 23:02

This animation also nicely illustrates the fact that, to find all the primes up to some maximum $n$, you only need to sieve out multiples of primes less than $\sqrt n$. (Here, $n = 120 < 11^2 = 121$, so the only primes whose multiples need to be sieved out are 2, 3, 5 and 7.) After that, all the remaining unsieved numbers will be primes. – Ilmari Karonen Jul 20 '14 at 22:45