# twin prime constant

If we look at the number of twin primes less than
*x* we see the usual irregularities associated
with distributions of primes:

but back up and look again and the distribution looks much smoother:

(Click here for a graph to 1,000,000).

Hardy and Littlewood conjectured that there are about

twin primes less than or equal to *x* where
the infinite product is the **twin prime constant**.
See the page "a simple heuristic" linked below for
information on how this conjecture is formed.

This constant was estimated by Wrench and others to be approximately 0.6601618158...

**See Also:** TwinPrime, BrunsConstant, PrimeKtupleConjecture

**Related pages** (outside of this work)

- Twin primes (records and research)
- A simple heuristic

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