Ormiston pairs: Difference between revisions

{{works with|ALGOL 68G|Any - tested with release 2.8.3.win32}}

{{libheader|ALGOL 68-primes}}

When running this with ALGOL 68G, you will need to specify a large heap size with e.g., <code>-heap 256M</code> on the ALGOL 68G command.

<syntaxhighlight lang="algol68">

BEGIN # find some Orimiston pairs - pairs of primes where the first and next #

# prime are anagrams #

PR read "primes.incl.A68" PR # include prime utilities #

INT max prime = 10 000 000; # maximum number we will consider #

INT max digits = BEGIN # count the digits of max prime #

d

END;

[]BOOL prime = PRIMESIEVE max prime;

# construct a list of the primes up to the maximum prime to consider #

[]INT prime list = EXTRACTPRIMESUPTO max prime FROMPRIMESIEVE prime;

BEGIN

WHILE ( v OVERAB 10 ) > 0 DO

END # get digits # ;

# count the Ormiston pairs #

INT o count := 0;

INT p1 = prime list[ i ];

INT p2 = prime list[ i + 1 ];

FI

OD;

END

</syntaxhighlight>

(65479, 65497) (66413, 66431) (74779, 74797)

(75913, 75931) (76213, 76231) (76579, 76597)

 

</pre>

 

382 Ormiston pairs less than a million.

</pre>

 

=={{header|Go}}==

"fmt"

"rcu"

)

 

func main() {

primes := rcu.Primes(limit)

var orm30 [][2]int

j := int(1e5)

count := 0

var counts []int

p1 := primes[i]

p2 := primes[i+1]

if (p2-p1)%18 != 0 {

continue

}

if count < 30 {

orm30 = append(orm30, [2]int{p1, p2})

}

count++

}

}

}

}

}</syntaxhighlight>

 

382 Ormiston pairs before 1,000,000

3,722 Ormiston pairs before 10,000,000

</pre>

 

=={{header|J}}==

For this, we would like to be able to test if a prime number is the first value in an Ormiston pair:

<syntaxhighlight lang=J> isorm=: -:&(/:~)&":&> 4 p: ]</syntaxhighlight>

 

Then the task becomes:

 

+/isorm i.&.(p:inv) 1e6 NB. number of Ormiston pairs less than 1e6

382

+/isorm i.&.(p:inv) 1e7 NB. number of Ormiston pairs less than 1e7

3722</syntaxhighlight>

 

=={{header|Raku}}==

use List::Divvy;

 

 

say "First thirty Ormiston pairs:";

382 Ormiston pairs before one million

3722 Ormiston pairs before ten million</pre>

 

=={{header|Wren}}==

{{libheader|Wren-math}}

{{libheader|Wren-fmt}}

import "./fmt" for Fmt

 

var primes = Int.primeSieve(limit)

var orm30 = []

var j = 1e5

var count = 0

var counts = []

var p1 = primes[i]

var p2 = primes[i+1]

if (count < 30) orm30.add([p1, p2])

if (p1 >= j) {

}

count = count + 1

}

}

System.print("First 30 Ormiston pairs:")

Fmt.tprint("[$,6d] ", orm30, 3)

 

{{out}}

382 Ormiston pairs before 1,000,000

3,722 Ormiston pairs before 10,000,000

</pre>