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