How it works

A precomputed prefix-sum table stores π(x) at every 30,000,000-number interval up to 2 × 10¹². The table (≈ 521 KB) is loaded into your browser. For any query, the nearest checkpoint is looked up in O(1), then a wheel-30 segmented sieve (compiled to WebAssembly for near-native speed) counts the remaining primes in the short gap.

Build your own table

The C++ source can build tables to any range on your hardware. Clone the repo, compile, and extend the table incrementally — each run only sieves the new range.