Safe primes and unsafe primes: Difference between revisions
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Count of unsafe primes below 1,000,000: 74,174
Count of unsafe primes below 10,000,000: 633,922
</pre>
=={{header|PureBasic}}==
<lang PureBasic>#MAX=10000000
Global Dim P.b(#MAX) : FillMemory(@P(),#MAX,1,#PB_Byte)
Global NewList Primes.i()
Global NewList SaveP.i()
Global NewList UnSaveP.i()
For n=2 To Sqr(#MAX)+1 : If P(n) : m=n*n : While m<=#MAX : P(m)=0 : m+n : Wend : EndIf : Next
For i=2 To #MAX : If p(i) : AddElement(Primes()) : Primes()=i : EndIf : Next
ForEach Primes()
If P((Primes()-1)/2) And Primes()>3 : AddElement(SaveP()) : SaveP()=Primes() : If Primes()<1000000 : c1+1 : EndIf
Else
AddElement(UnSaveP()) : UnSaveP()=Primes() : If Primes()<1000000 : c2+1 : EndIf
EndIf
Next
OpenConsole()
PrintN("First 35 safe primes:")
If FirstElement(SaveP())
For i=1 To 35 : Print(Str(SaveP())+" ") : NextElement(SaveP()) : Next
EndIf
PrintN(~"\nThere are "+FormatNumber(c1,0,".","'")+" safe primes below 1'000'000")
PrintN("There are "+FormatNumber(ListSize(SaveP()),0,".","'")+" safe primes below 10'000'000")
PrintN("")
PrintN("First 40 unsafe primes:")
If FirstElement(UnSaveP())
For i=1 To 40 : Print(Str(UnSaveP())+" ") : NextElement(UnSaveP()) : Next
EndIf
PrintN(~"\nThere are "+FormatNumber(c2,0,".","'")+" unsafe primes below 1'000'000")
PrintN("There are "+FormatNumber(ListSize(UnSaveP()),0,".","'")+" unsafe primes below 10'000'000")
Input()</lang>
{{out}}
<pre>First 35 safe primes:
5 7 11 23 47 59 83 107 167 179 227 263 347 359 383 467 479 503 563 587 719 839 863 887 983 1019 1187 1283 1307 1319 1367 1439 1487 1523 1619
There are 4'324 safe primes below 1'000'000
There are 30'657 safe primes below 10'000'000
First 40 unsafe primes:
2 3 13 17 19 29 31 37 41 43 53 61 67 71 73 79 89 97 101 103 109 113 127 131 137 139 149 151 157 163 173 181 191 193 197 199 211 223 229 233
There are 74'174 unsafe primes below 1'000'000
There are 633'922 unsafe primes below 10'000'000
</pre>
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