Perfect numbers: Difference between revisions
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=={{header|PARI/GP}}== |
=={{header|PARI/GP}}== |
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===Using built-in |
===Using built-in methods=== |
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<syntaxhighlight lang="parigp"> |
<syntaxhighlight lang="parigp"> |
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isPerfect(n)=sigma(n,-1)==2 |
isPerfect(n)=sigma(n,-1)==2 |
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Show perfect numbers |
Show perfect numbers |
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<syntaxhighlight lang="parigp"> |
<syntaxhighlight lang="parigp"> |
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forprime(p=2, 2281, |
forprime(p=2, 2281, |
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print(p"\t",(2^p-1)*2^(p-1)))) |
print(p"\t",(2^p-1)*2^(p-1)))) |
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</syntaxhighlight> |
</syntaxhighlight> |
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faster alternative showing them still using built-in methods |
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<syntaxhighlight lang="parigp"> |
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[n|n<-[1..10^4],sigma(n,-1)==2] |
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</syntaxhighlight> |
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===Faster with Lucas-Lehmer test=== |
===Faster with Lucas-Lehmer test=== |
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<syntaxhighlight lang="parigp">p=2;n=3;n1=2; |
<syntaxhighlight lang="parigp">p=2;n=3;n1=2; |
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