Perfect numbers: Difference between revisions
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Thundergnat (talk | contribs) (→{{header|Perl 6}}: Add a much faster variation) |
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=={{header|Perl 6}}== |
=={{header|Perl 6}}== |
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Naive (very slow) version |
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<lang perl6>sub is-perf($n) { $n == [+] grep $n %% *, 1 .. $n div 2 } |
<lang perl6>sub is-perf($n) { $n == [+] grep $n %% *, 1 .. $n div 2 } |
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# used as |
# used as |
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put (grep {.&is-perf} |
put ((1..Inf).hyper.grep: {.&is-perf})[^4];</lang> |
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{{out}} |
{{out}} |
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<pre>6 28 496 8128</pre> |
<pre>6 28 496 8128</pre> |
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Much, much faster version: |
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<lang perl6>my @primes = lazy 2,3,*+2 … Inf; |
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my @perfects = lazy gather for @primes { |
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my $n = 2**$_ - 1; |
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take $n * 2**($_ - 1) if $n.is-prime; |
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} |
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.put for @perfects[^12];</lang> |
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{{out}} |
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<pre>6 |
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28 |
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496 |
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8128 |
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33550336 |
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8589869056 |
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137438691328 |
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2305843008139952128 |
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2658455991569831744654692615953842176 |
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191561942608236107294793378084303638130997321548169216 |
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13164036458569648337239753460458722910223472318386943117783728128 |
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14474011154664524427946373126085988481573677491474835889066354349131199152128</pre> |
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=={{header|Phix}}== |
=={{header|Phix}}== |
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