Prime numbers

▸ Spreading the numbers 1 … N onto the grid…

▸ Loading the Sieve of Eratosthenes

▸ Building the Ulam spiral from the center

▸ Measuring density & the x∕ln x estimate

▸ Filtering the numbers divisible only by 1 & themselves…

▸ Ready — Online. ✅

Count & density

🔢 Sieve of Eratosthenes

prime density by block

Range (N)—

Primes found—

Density—

Sieving multiples of—

Estimate N∕ln N—

Largest prime—

Tip

Each cell is a natural number. A bright green number = prime (divisible only by 1 & itself); a dim number = composite, crossed off as a multiple of a smaller number. Primes thin out as you go further.

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Hover a cell = see the number & its divisors · click = factorize · adjust speed & range on the right

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Prime density per block (falls as N grows) actual densityestimate 1∕ln x