# Mersenne primes

Mersenne primes is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Mersenne primes:

Challenge:

Create code that will list (preferably calculate) all of the Mersenne primes until some limitation is reached. For information on what a Mersenne prime is, go to this link: [[1]]

## AppleScript

` on isPrime(integ)	set isComposite to ""	if (integ / 2) = (integ / 2 div 1) then		log integ & " is composite because 2 is a factor" as string --buttons {"OK", "Cancel"} default button 1 cancel button 2 	else		set x to 2		set sqrtOfInteg to integ ^ 0.5		repeat until x = integ ^ 0.5 + 1 as integer			if (integ / x) = integ / x div 1 then				log integ & " is composite because " & x & " & " & (integ / x div 1) & " are factors" as string --buttons {"OK", "Cancel"} default button 1 cancel button 2				set isComposite to 1				set x to x + 1			else 				set x to x + 1			end if   		end repeat		log integ & " is prime" as string --buttons {"OK", "Cancel"} default button 1 cancel button 2		if isComposite = 1 then			log integ & "is composite"		else			display dialog integ		end if	end if end isPrimeset x to 2repeat	isPrime(((2 ^ x) - 1) div 1)	set x to x + 1end repeat `

## C#

Needs a better primality checking algorithm to do really large prime numbers.

`using System;using System.Numerics; namespace MersennePrimes {    class Program {        static BigInteger Sqrt(BigInteger x) {            if (x < 0) throw new ArgumentException("Negative argument.");            if (x < 2) return x;            BigInteger y = x / 2;            while (y > x / y) {                y = ((x / y) + y) / 2;            }            return y;        }         static bool IsPrime(BigInteger bi) {            if (bi < 2) return false;            if (bi % 2 == 0) return bi == 2;            if (bi % 3 == 0) return bi == 3;            if (bi % 5 == 0) return bi == 5;            if (bi % 7 == 0) return bi == 7;            if (bi % 11 == 0) return bi == 11;            if (bi % 13 == 0) return bi == 13;            if (bi % 17 == 0) return bi == 17;            if (bi % 19 == 0) return bi == 19;             BigInteger limit = Sqrt(bi);            BigInteger test = 23;            while (test < limit) {                if (bi % test == 0) return false;                test += 2;                if (bi % test == 0) return false;                test += 4;            }             return true;        }         static void Main(string[] args) {            const int MAX = 9;             int pow = 2;            int count = 0;             while (true) {                if (IsPrime(pow)) {                    BigInteger p = BigInteger.Pow(2, pow) - 1;                    if (IsPrime(p)) {                        Console.WriteLine("2 ^ {0} - 1", pow);                        if (++count >= MAX) {                            break;                        }                    }                }                pow++;            }        }    }}`
Output:
```2 ^ 2 - 1
2 ^ 3 - 1
2 ^ 5 - 1
2 ^ 7 - 1
2 ^ 13 - 1
2 ^ 17 - 1
2 ^ 19 - 1
2 ^ 31 - 1
2 ^ 61 - 1```

## D

Simplest thing that could possibly work. Using better primality tests will allow for more results to be calculated in a reasonable amount of time.

`import std.bigint;import std.stdio; bool isPrime(BigInt bi) {    if (bi < 2) return false;    if (bi % 2 == 0) return bi == 2;    if (bi % 3 == 0) return bi == 3;     auto test = BigInt(5);    while (test * test < bi) {        if (bi % test == 0) return false;        test += 2;        if (bi % test == 0) return false;        test += 4;    }     return true;} void main() {    auto base = BigInt(2);     for (int pow=1; pow<32; pow++) {        if (isPrime(base-1)) {            writeln("2 ^ ", pow, " - 1");        }        base *= 2;    }}`
Output:
```2 ^ 2 - 1
2 ^ 3 - 1
2 ^ 5 - 1
2 ^ 7 - 1
2 ^ 13 - 1
2 ^ 17 - 1
2 ^ 19 - 1
2 ^ 31 - 1```

## Go

The `github.com/ncw/gmp` package is a drop-in replacement for Go's `math/big` package. It's a CGo wrapper around the C GMP library and under these circumstances is two to four times as fast as the native Go package. Editing just the import line you can use whichever is more convenient for you (CGo has drawbacks, including limited portability). Normally build tags would be used to control this instead of editing imports in the source, but this keeps the example simpler.

Note that the use of ProbablyPrime(0) requires Go 1.8 or later. When using the `math/big` package, passing a parameter of zero to this method forces it to apply only the Baillie-PSW test to check for primality. This is 100% accurate for numbers up to 2^64 and at the time of writing (June 2018) no known composite number above that bound passes the test.

`package main import (	"fmt"	"time" 	// Use one or the other of these:	"math/big"	//big "github.com/ncw/gmp") func main() {	start := time.Now()	one := big.NewInt(1)	mp := big.NewInt(0)	bp := big.NewInt(0)	const max = 22	for count, p := 0, uint(2); count < max; {		mp.Lsh(one, p)		mp.Sub(mp, one)		if mp.ProbablyPrime(0) {			elapsed := time.Since(start).Seconds()			if elapsed >= 0.01 {				fmt.Printf("2 ^ %-4d - 1 took %6.2f secs\n", p, elapsed)			} else {				fmt.Printf("2 ^ %-4d - 1\n", p)			}			count++		}		for {			if p > 2 {				p += 2			} else {				p = 3			}			bp.SetUint64(uint64(p))			if bp.ProbablyPrime(0) {				break			}		}	}}`
Output using the GMP package on a 3.4 GHz Xeon E3-1245:
```2 ^ 2    - 1
2 ^ 3    - 1
2 ^ 5    - 1
2 ^ 7    - 1
2 ^ 13   - 1
2 ^ 17   - 1
2 ^ 19   - 1
2 ^ 31   - 1
2 ^ 61   - 1
2 ^ 89   - 1
2 ^ 107  - 1
2 ^ 127  - 1
2 ^ 521  - 1
2 ^ 607  - 1
2 ^ 1279 - 1 took   0.05 secs
2 ^ 2203 - 1 took   0.38 secs
2 ^ 2281 - 1 took   0.44 secs
2 ^ 3217 - 1 took   1.53 secs
2 ^ 4253 - 1 took   4.39 secs
2 ^ 4423 - 1 took   5.02 secs
2 ^ 9689 - 1 took  73.78 secs
2 ^ 9941 - 1 took  81.24 secs
```

(A previous run on more modest hardware - Celeron N3050 @ 1.60GHz × 2 - was ~365 seconds for M9941.)

This can be sped up quite a bit for modern multi-core CPUs by some simple changes to use goroutines.

`package main import (	"fmt"	"runtime"	"time" 	// Use one or the other of these:	"math/big"	//big "github.com/ncw/gmp") func main() {	start := time.Now() 	nworkers := runtime.GOMAXPROCS(0)	fmt.Println("Using", nworkers, "workers.")	workC := make(chan uint, 1)	resultC := make(chan uint, nworkers) 	// Generate possible Mersenne exponents and send them to workC.	go func() {		workC <- 2		bp := big.NewInt(0)		for p := uint(3); ; p += 2 {			// Possible exponents must be prime.			bp.SetUint64(uint64(p))			if bp.ProbablyPrime(0) {				workC <- p			}		}	}() 	// Start up worker go routines, each takes	// possible Mersenne exponents from workC as `p`	// and if 2^p-1 is prime sends `p` to resultC.	one := big.NewInt(1)	for i := 0; i < nworkers; i++ {		go func() {			mp := big.NewInt(0)			for p := range workC {				mp.Lsh(one, p)				mp.Sub(mp, one)				if mp.ProbablyPrime(0) {					resultC <- p				}			}		}()	} 	// Receive some maximum number of Mersenne prime exponents	// from resultC and show the Mersenne primes.	const max = 24	for count := 0; count < max; count++ {		// Note: these could come back out of order, although usually		// only the first few. If that is an issue, correcting it is		// left as an excercise to the reader :).		p := <-resultC		elapsed := time.Since(start).Seconds()		if elapsed >= 0.01 {			fmt.Printf("2 ^ %-5d - 1 took %6.2f secs\n", p, elapsed)		} else {			fmt.Printf("2 ^ %-5d - 1\n", p)		}	}}`
Output using the GMP package on the same 3.4 GHz Xeon E3-1245 (4 core × 2 SMT threads) as above:
```Using 8 workers.
2 ^ 2     - 1
2 ^ 5     - 1
2 ^ 3     - 1
2 ^ 7     - 1
2 ^ 13    - 1
2 ^ 19    - 1
2 ^ 61    - 1
2 ^ 31    - 1
2 ^ 107   - 1
2 ^ 17    - 1
2 ^ 127   - 1
2 ^ 89    - 1
2 ^ 521   - 1
2 ^ 607   - 1
2 ^ 1279  - 1 took   0.01 secs
2 ^ 2203  - 1 took   0.09 secs
2 ^ 2281  - 1 took   0.12 secs
2 ^ 3217  - 1 took   0.36 secs
2 ^ 4253  - 1 took   0.94 secs
2 ^ 4423  - 1 took   1.06 secs
2 ^ 9689  - 1 took  16.28 secs
2 ^ 9941  - 1 took  18.02 secs
2 ^ 11213 - 1 took  26.76 secs
2 ^ 19937 - 1 took 194.16 secs
```

Using this approach, the Celeron machine (dual core) takes ~180 seconds to reach M9941 and ~270 seconds to reach M11213.

## Java

Translation of: Kotlin
`import java.math.BigInteger; public class MersennePrimes {    private static final int MAX = 20;     private static final BigInteger ONE = BigInteger.ONE;    private static final BigInteger TWO = BigInteger.valueOf(2);     private static boolean isPrime(int n) {        if (n < 2) return false;        if (n % 2 == 0) return n == 2;        if (n % 3 == 0) return n == 3;        int d = 5;        while (d * d <= n) {            if (n % d == 0) return false;            d += 2;            if (n % d == 0) return false;            d += 4;        }        return true;    }     public static void main(String[] args) {        int count = 0;        int p = 2;        while (true) {            BigInteger m = TWO.shiftLeft(p - 1).subtract(ONE);            if (m.isProbablePrime(10)) {                System.out.printf("2 ^ %d - 1\n", p);                if (++count == MAX) break;            }            // obtain next prime, p            do {                p = (p > 2) ? p + 2 : 3;            } while (!isPrime(p));        }    }}`
Output:
```2 ^ 2 - 1
2 ^ 3 - 1
2 ^ 5 - 1
2 ^ 7 - 1
2 ^ 13 - 1
2 ^ 17 - 1
2 ^ 19 - 1
2 ^ 31 - 1
2 ^ 61 - 1
2 ^ 89 - 1
2 ^ 107 - 1
2 ^ 127 - 1
2 ^ 521 - 1
2 ^ 607 - 1
2 ^ 1279 - 1
2 ^ 2203 - 1
2 ^ 2281 - 1
2 ^ 3217 - 1
2 ^ 4253 - 1
2 ^ 4423 - 1```

## Julia

Works with: Julia version 0.6

Julia module `Primes` uses Miller-Rabin primality test.

`using Primes mersenne(n::Integer) = convert(typeof(n), 2) ^ n - one(n)function main(nmax::Integer)    n = ith = zero(nmax)    while ith ≤ nmax        if isprime(mersenne(n))            println("M\$n")            ith += 1        end        n += 1    endend main(big(20))`
Output:
```M2
M3
M5
M7
M13
M17
M19
M31
M61
M89
M107
M127
M521
M607
M1279
M2203
M2281
M3217
M4253
M4423
M9689```

## Kotlin

This task is similar to the Lucas-Lehmer test task except that you can use whatever method you like to test the primality of the Mersenne numbers. Here, I've chosen to use the JDK's BigInteger.isProbablePrime(certainty) method. The exact algorithm is implementation dependent --- GNU classpath uses only Miller-Rabin, while Oracle JDK uses Miller-Rabin and sometimes adds a Lucas test (this is not the Lucas-Lehmer test).

A 'certainty' parameter of 10 is enough to find the first 20 Mersenne primes but as even this takes about 90 seconds on my modest machine I've not bothered going beyond that.

`// version 1.2.10 import java.math.BigInteger const val MAX = 20 val bigOne = BigInteger.ONEval bigTwo = 2.toBigInteger() /* for checking 'small' primes */fun isPrime(n: Int): Boolean {    if (n < 2) return false    if (n % 2 == 0) return n == 2    if (n % 3 == 0) return n == 3    var d : Int = 5    while (d * d <= n) {        if (n % d == 0) return false        d += 2        if (n % d == 0) return false        d += 4    }    return true} fun main(args: Array<String>) {    var count = 0    var p = 2    while (true) {        val m = (bigTwo shl (p - 1)) - bigOne        if (m.isProbablePrime(10)) {            println("2 ^ \$p - 1")            if (++count == MAX) break        }        // obtain next prime, p        while(true) {            p = if (p > 2) p + 2 else 3            if (isPrime(p)) break        }    }}`
Output:
```2 ^ 2 - 1
2 ^ 3 - 1
2 ^ 5 - 1
2 ^ 7 - 1
2 ^ 13 - 1
2 ^ 17 - 1
2 ^ 19 - 1
2 ^ 31 - 1
2 ^ 61 - 1
2 ^ 89 - 1
2 ^ 107 - 1
2 ^ 127 - 1
2 ^ 521 - 1
2 ^ 607 - 1
2 ^ 1279 - 1
2 ^ 2203 - 1
2 ^ 2281 - 1
2 ^ 3217 - 1
2 ^ 4253 - 1
2 ^ 4423 - 1
```

## PARI/GP

`LL(p)={  my(m=Mod(4,1<<p-1));  for(i=3,p,m=m^2-2);  m==0};forprime(p=2,, if(LL(p), print("2^"p"-1")))`

## Perl

Since GIMPS went to the trouble of dedicating thousands of CPU years to finding Mersenne primes, we should be kind enough to use the results. The ntheory module front end does this, so the results up to 43 million is extremely fast (4 seconds), and we can reduce this another 10x by only checking primes. After the GIMPS double-checked mark, a Lucas-Lehmer test is done using code similar to Rosetta Code Lucas-Lehmer in C+GMP.

If this is too contrived, we can use `Math::Prime::Util::GMP::is_mersenne_prime` instead, which will run the Lucas-Lehmer test on each input. The first 23 Mersenne primes are found in under 15 seconds.

Library: ntheory
`use ntheory qw/forprimes is_mersenne_prime/;forprimes { is_mersenne_prime(\$_) && say } 1e9;`
Output:
```2
3
5
7
13
17
19
31
61
...
```

## Perl 6

Works with: Rakudo version 2018.01

We already have a multitude of tasks that demonstrate how to find Mersenne primes; Prime decomposition, Primality by trial division, Trial factoring of a Mersenne number, Lucas-Lehmer test, Miller–Rabin primality_test, etc. that all have Perl 6 entries. I'm not sure what I could add here that would be useful.

Hmmm.

Create code that will list all of the Mersenne primes until some limitation is reached.

It doesn't specify to calculate them, only to list them; why throw away all of the computer millenia of processing power that the GIMPS has invested?

`use HTTP::UserAgent;use Gumbo; my \$table = parse-html(HTTP::UserAgent.new.get('https://www.mersenne.org/primes/').content, :TAG<table>); say 'All known Mersenne primes as of ', Date(now); say 'M', ++\$, ": 2\$_ - 1"  for \$table[1]».[*][0][*].comb(/'exp_lo='\d+/)».subst(/\D/, '',:g)  .trans([<0123456789>.comb] => [<⁰¹²³⁴⁵⁶⁷⁸⁹>.comb]).words; `
Output:
```All known Mersenne primes as of 2018-12-21
M1: 2² - 1
M2: 2³ - 1
M3: 2⁵ - 1
M4: 2⁷ - 1
M5: 2¹³ - 1
M6: 2¹⁷ - 1
M7: 2¹⁹ - 1
M8: 2³¹ - 1
M9: 2⁶¹ - 1
M10: 2⁸⁹ - 1
M11: 2¹⁰⁷ - 1
M12: 2¹²⁷ - 1
M13: 2⁵²¹ - 1
M14: 2⁶⁰⁷ - 1
M15: 2¹²⁷⁹ - 1
M16: 2²²⁰³ - 1
M17: 2²²⁸¹ - 1
M18: 2³²¹⁷ - 1
M19: 2⁴²⁵³ - 1
M20: 2⁴⁴²³ - 1
M21: 2⁹⁶⁸⁹ - 1
M22: 2⁹⁹⁴¹ - 1
M23: 2¹¹²¹³ - 1
M24: 2¹⁹⁹³⁷ - 1
M25: 2²¹⁷⁰¹ - 1
M26: 2²³²⁰⁹ - 1
M27: 2⁴⁴⁴⁹⁷ - 1
M28: 2⁸⁶²⁴³ - 1
M29: 2¹¹⁰⁵⁰³ - 1
M30: 2¹³²⁰⁴⁹ - 1
M31: 2²¹⁶⁰⁹¹ - 1
M32: 2⁷⁵⁶⁸³⁹ - 1
M33: 2⁸⁵⁹⁴³³ - 1
M34: 2¹²⁵⁷⁷⁸⁷ - 1
M35: 2¹³⁹⁸²⁶⁹ - 1
M36: 2²⁹⁷⁶²²¹ - 1
M37: 2³⁰²¹³⁷⁷ - 1
M38: 2⁶⁹⁷²⁵⁹³ - 1
M39: 2¹³⁴⁶⁶⁹¹⁷ - 1
M40: 2²⁰⁹⁹⁶⁰¹¹ - 1
M41: 2²⁴⁰³⁶⁵⁸³ - 1
M42: 2²⁵⁹⁶⁴⁹⁵¹ - 1
M43: 2³⁰⁴⁰²⁴⁵⁷ - 1
M44: 2³²⁵⁸²⁶⁵⁷ - 1
M45: 2³⁷¹⁵⁶⁶⁶⁷ - 1
M46: 2⁴²⁶⁴³⁸⁰¹ - 1
M47: 2⁴³¹¹²⁶⁰⁹ - 1
M48: 2⁵⁷⁸⁸⁵¹⁶¹ - 1
M49: 2⁷⁴²⁰⁷²⁸¹ - 1
M50: 2⁷⁷²³²⁹¹⁷ - 1
M51: 2⁸²⁵⁸⁹⁹³³ - 1```

## Python

Translation of: Java
`import random #Take from https://www.codeproject.com/Articles/691200/%2FArticles%2F691200%2FPrimality-test-algorithms-Prime-test-The-fastest-wdef MillerRabinPrimalityTest(number):    '''    because the algorithm input is ODD number than if we get    even and it is the number 2 we return TRUE ( spcial case )    if we get the number 1 we return false and any other even     number we will return false.    '''    if number == 2:        return True    elif number == 1 or number % 2 == 0:        return False     ''' first we want to express n as : 2^s * r ( were r is odd ) '''     ''' the odd part of the number '''    oddPartOfNumber = number - 1     ''' The number of time that the number is divided by two '''    timesTwoDividNumber = 0     ''' while r is even divid by 2 to find the odd part '''    while oddPartOfNumber % 2 == 0:        oddPartOfNumber = oddPartOfNumber / 2        timesTwoDividNumber = timesTwoDividNumber + 1      '''    since there are number that are cases of "strong liar" we     need to check more then one number    '''    for time in range(3):         ''' choose "Good" random number '''        while True:            ''' Draw a RANDOM number in range of number ( Z_number )  '''            randomNumber = random.randint(2, number)-1            if randomNumber != 0 and randomNumber != 1:                break         ''' randomNumberWithPower = randomNumber^oddPartOfNumber mod number '''        randomNumberWithPower = pow(randomNumber, oddPartOfNumber, number)         ''' if random number is not 1 and not -1 ( in mod n ) '''        if (randomNumberWithPower != 1) and (randomNumberWithPower != number - 1):            # number of iteration            iterationNumber = 1             ''' while we can squre the number and the squered number is not -1 mod number'''            while (iterationNumber <= timesTwoDividNumber - 1) and (randomNumberWithPower != number - 1):                ''' squre the number '''                randomNumberWithPower = pow(randomNumberWithPower, 2, number)                 # inc the number of iteration                iterationNumber = iterationNumber + 1            '''                 if x != -1 mod number then it because we did not found strong witnesses            hence 1 have more then two roots in mod n ==>            n is composite ==> return false for primality            '''            if (randomNumberWithPower != (number - 1)):                return False     ''' well the number pass the tests ==> it is probably prime ==> return true for primality '''    return True # MainMAX = 20p = 2count = 0while True:    m = (2 << (p - 1)) - 1    if MillerRabinPrimalityTest(m):        print "2 ^ {} - 1".format(p)        count = count + 1        if count == MAX:            break    # obtain next prime, p    while True:        p = p + 2 if (p > 2) else 3        if MillerRabinPrimalityTest(p):            breakprint "done"`
Output:
```2 ^ 2 - 1
2 ^ 3 - 1
2 ^ 5 - 1
2 ^ 7 - 1
2 ^ 13 - 1
2 ^ 17 - 1
2 ^ 19 - 1
2 ^ 31 - 1
2 ^ 61 - 1
2 ^ 89 - 1
2 ^ 107 - 1
2 ^ 127 - 1
2 ^ 521 - 1
2 ^ 607 - 1
2 ^ 1279 - 1
2 ^ 2203 - 1
2 ^ 2281 - 1
2 ^ 3217 - 1
2 ^ 4253 - 1
2 ^ 4423 - 1
done```

## REXX

This REXX version   (using a 32-bit Regina REXX interpreter)   will find those Mersenne primes which are less than
8 million decimal digits   (which would be M43).

`/*REXX program uses  exponent─and─mod  operator to test possible Mersenne numbers.      */      do j=1;                                    /*process a range,  or run out of time.*/      if \isPrime(j)  then iterate               /*if  J  isn't a prime,  keep plugging.*/      r= testMer(j)                              /*If J is prime, give J the 3rd degree.*/      if r==0   then  say right('M'j, 10)     "──────── is a Mersenne prime."                else  say right('M'j, 50)     "is composite, a factor:"   r      end   /*j*/exit                                             /*stick a fork in it,  we're all done. *//*──────────────────────────────────────────────────────────────────────────────────────*/isPrime: procedure; parse arg x;             if wordpos(x, '2 3 5 7') \== 0  then return 1         if x<11  then return 0;             if x//2 == 0 | x//3       == 0  then return 0              do j=5  by 6;                  if x//j == 0 | x//(j+2)   == 0  then return 0              if j*j>x   then return 1                 /*◄─┐         ___                */              end   /*j*/                              /*  └─◄ Is j>√ x ?  Then return 1*//*──────────────────────────────────────────────────────────────────────────────────────*/iSqrt:   procedure; parse arg x;  #= 1;      r= 0;             do while #<=x;  #=#*4;  end           do while #>1;  #=#%4;  _= x-r-#;  r= r%2;  if _>=0  then do;  x=_;  r=r+#;  end           end   /*while*/                             /*iSqrt ≡    integer square root.*/         return r                                      /*─────      ─       ──     ─  ─ *//*──────────────────────────────────────────────────────────────────────────────────────*/testMer: procedure;  parse arg x;              p =2**x /* [↓]  do we have enough digits?*/         \$\$=x2b( d2x(x) ) + 0         if pos('E',p)\==0  then do; parse var p "E" _;  numeric digits _+2;  p=2**x;  end         !.=1;  !.1=0;  !.7=0                          /*array used for a quicker test. */         R=iSqrt(p)                                    /*obtain integer square root of P*/                    do k=2  by 2;        q=k*x  +  1   /*(shortcut) compute value of Q. */                    m=q // 8                           /*obtain the remainder when ÷ 8. */                    if !.m               then iterate  /*M  must be either one or seven.*/                    parse var q '' -1 _; if _==5  then iterate      /*last digit a five?*/                    if q// 3==0  then iterate                       /*    ÷   by three? */                    if q// 7==0  then iterate                       /*    "    " seven? */                    if q//11==0  then iterate                       /*    "    " eleven?*/                                                       /*      ____                     */                    if q>R               then return 0 /*Is q>√2**x ?   A Mersenne prime*/                    sq=1;         \$=\$\$                 /*obtain binary version from  \$. */                        do  until \$=='';      sq=sq*sq                        parse var \$  _  2  \$           /*obtain 1st digit and the rest. */                        if _  then sq=(sq+sq) // q                        end   /*until*/                    if sq==1  then return q            /*Not a prime?   Return a factor.*/                    end   /*k*/`

## Ring

` # Project : Mersenne primes n = 0while true        n = n +1        if isprime(pow(2,n)-1) = 1           see n + nl        okend func isprime num       if (num <= 1) return 0 ok       if (num % 2 = 0) and num != 2 return 0 ok       for i = 3 to floor(num / 2) -1 step 2            if (num % i = 0) return 0 ok       next       return 1 `

Output:

```2
3
5
7
13
17
19
```

## Scala

`object MersennePrimes extends App {  import Stream._   def primeSieve(s: Stream[Int]): Stream[Int] =    s.head #:: primeSieve(s.tail filter { _ % s.head != 0 })  val primes = primeSieve(from(2))   def mersenne(p: Int): BigInt = (BigInt(2) pow p) - 1   def s(mp: BigInt, p: Int): BigInt = { if (p == 1) 4 else ((s(mp, p - 1) pow 2) - 2) % mp }   val upbPrime = 9941  println(s"Finding Mersenne primes in M[2..\$upbPrime]")  ((primes takeWhile (_ <= upbPrime)).par map { p => (p, mersenne(p)) }    map { p => if (p._1 == 2) (p, 0) else (p, s(p._2, p._1 - 1)) } filter { _._2 == 0 })    .foreach { p =>      println(s"prime M\${(p._1)._1}: " +        { if ((p._1)._1 < 200) (p._1)._2 else s"(\${(p._1)._2.toString.size} digits)" })    }  println("That's All Folks!")}`

## Sidef

Uses the is_mersenne_prime() function from Math::Prime::Util::GMP.

`for p in (^Inf -> lazy.grep { .is_mersenne_prime }) {    say "2^#{p} - 1"}`
Output:
```2^2 - 1
2^3 - 1
2^5 - 1
2^7 - 1
2^13 - 1
2^17 - 1
2^19 - 1
2^31 - 1
2^61 - 1
2^89 - 1
2^107 - 1
2^127 - 1
2^521 - 1
2^607 - 1
2^1279 - 1
2^2203 - 1
2^2281 - 1
2^3217 - 1
2^4253 - 1
2^4423 - 1
2^9689 - 1
2^9941 - 1
^C
sidef mersenne.sf  12.47s user 0.02s system 99% cpu 12.495 total
```

## zkl

Library: GMP

Uses libGMP (GNU MP Bignum Library) and its Miller-Rabin probabilistic primality testing algorithm.

`var [const] BN=Import.lib("zklBigNum");  // libGMPfcn mprimes{   n,m := BN(2),0;   foreach e in ([2..]){      n,m = n.shiftLeft(1), n-1;      if(m.probablyPrime()) println("2^%d - 1".fmt(e));   }}()// gets rather slow after M(4423)`
Output:
```2^2 - 1
2^3 - 1
2^5 - 1
2^7 - 1
2^13 - 1
2^17 - 1
2^19 - 1
2^31 - 1
2^61 - 1
2^89 - 1
2^107 - 1
2^127 - 1
2^521 - 1
2^607 - 1
2^1279 - 1
2^2203 - 1
2^2281 - 1
2^3217 - 1
2^4253 - 1
2^4423 - 1
2^9689 - 1
2^9941 - 1
2^11213 - 1
...
```