Special neighbor primes: Difference between revisions
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{{Draft task}}
;Task:Let ('''p<sub>1</sub>''', '''p<sub>2</sub>''') are neighbourprimes. Find and show here in base ten '''p<sub>1</sub> + p<sub>2</sub> - 1''' where '''p<sub>1</sub>, p<sub>2</sub> < 100'''.
<br><br>
=={{header|Ring}}==
<lang ring>
load "stdlib.ring"
see "working..." + nl
see "Special neighbour primes are:" + nl
row = 0
oldPrime = 2
for n = 3 to 100
if isprime(n) and isprime(oldPrime)
sum = oldPrime + n - 1
if isprime(sum)
row++
see "" + oldPrime + "," + n + " => " + sum + nl
ok
oldPrime = n
ok
next
see "Found " + row + " special neighbour primes"
see "done..." + nl
</lang>
{{out}}
<pre>
working...
Special twin primes are:
3,5 => 7
5,7 => 11
7,11 => 17
11,13 => 23
13,17 => 29
19,23 => 41
29,31 => 59
31,37 => 67
41,43 => 83
43,47 => 89
61,67 => 127
67,71 => 137
73,79 => 151
Found 13 special twin primesdone...
</pre>
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Revision as of 04:54, 6 August 2021
Special neighbor 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.
- Task
- Let (p1, p2) are neighbourprimes. Find and show here in base ten p1 + p2 - 1 where p1, p2 < 100.
Ring
<lang ring> load "stdlib.ring"
see "working..." + nl see "Special neighbour primes are:" + nl row = 0 oldPrime = 2
for n = 3 to 100
if isprime(n) and isprime(oldPrime) sum = oldPrime + n - 1 if isprime(sum) row++ see "" + oldPrime + "," + n + " => " + sum + nl ok oldPrime = n ok
next
see "Found " + row + " special neighbour primes" see "done..." + nl </lang>
- Output:
working... Special twin primes are: 3,5 => 7 5,7 => 11 7,11 => 17 11,13 => 23 13,17 => 29 19,23 => 41 29,31 => 59 31,37 => 67 41,43 => 83 43,47 => 89 61,67 => 127 67,71 => 137 73,79 => 151 Found 13 special twin primesdone...