Indeed, the primes program uses Eratosthenes sieve using pre-calculated array of primes up to 65537, leading to possible errors (and, in this case real errors, as 65539 is also a prime) when range hits (65537+2)^2.
There are a few possible fixes, that I can think of: a) don't support 64-bit numbers, set upper limit to UINT32_MAX b) support 64-bit numbers, but set upper limit to (MAX(primes) + 2)**2 - 1 c) add some number of pre-calculated primes to array, and repeat b (supporting the whole 64-bit range would take 203280221 primes (which could be stored in a 4-byte uints, leading to ~800 megabytes of memory) d) recursively use the sieve to prime itself to reach unlimited range (this adds computation time and algorithm complexity) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/725367 Title: primes returns composites To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/bsdgames/+bug/725367/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
