Re: primepi(2^35)

On Tue 6 Jan, 2026, at 18:28, Ruud H.G. van Tol wrote:

? default(primelimit)
% 2000000000

? primepi(2^35)
cpu time = 18,133 ms, real time = 18,162 ms.
% 1480206279

? primepi(10^11)
cpu time = 4,744 ms, real time = 4,752 ms.
% 4118054813

Q: Why is the bigger value returned faster?

Because there is a table of precomputed pairs primepi/prime. If you fall near one

of the precomputed values, the computation is faster.

Happy new year,

Loïc

? prime(1480206279)
cpu time = 18,874 ms, real time = 18,937 ms.
% 34359738337

? prime(4118054813)
cpu time = 4,909 ms, real time = 4,917 ms.
% 99999999977