The IthMersenne(i) command returns the ith smallest number $n$ such that $2^n-1$ is known to be prime.

If $2^n-1$ is prime, then it is said to be a Mersenne prime.

There are currently 51 known Mersenne primes, but the rankings of the forty-fifth to fiftieth Mersenne primes are provisional, since there might be undiscovered Mersenne primes greater than the forty-fourth but less than the fiftieth.

An error will be displayed if i is greater than $51$.

$\mathrm{with}\left(\mathrm{NumberTheory}\right)\:$

$\mathrm{IthMersenne}\left(1\right)$

$2$

$\mathrm{IthMersenne}\left(35\right)$

$1398269$

$\mathrm{IthMersenne}\left(49\right)$

$74207281$

$\mathrm{IthMersenne}\left(52\right)$

Error, (in NumberTheory:-IthMersenne) only 51 Mersenne primes are known

The NumberTheory[IthMersenne] command was introduced in Maple 2016.

For more information on Maple 2016 changes, see Updates in Maple 2016.