- Usage:
`isPseudoprime x`

- Function: isPseudoprime
- Inputs:
`x`, an integer

- Outputs:
- a Boolean value, true if
`x`is a strong pseudoprime in the sense of Baillie-Pomerance-Selfridge-Wagstaff

- a Boolean value, true if

The algorithm is provided by pari. The pseudoprimality test means that it has no small factors, that it is a Rabin-Miller pseudoprime for the base $2$, and that it passes the strong Lucas test for the sequence $(P, -1)$, where $P$ is the smallest positive integer such that $P^2 - 4$ is not a square modulo $x$. Such pseudoprimes may not be prime; to check primality, use isPrime. According to the documentation of pari, such pseudoprimes are known to be prime up to *10 ^{13}*, and no nonprime pseudoprime is known.