Ulam numbers: Difference between revisions
Added Perl
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</pre>
=={{header|Perl}}==
{{trans|Julia}}
<lang perl>use strict;
use warnings;
use feature <say state>;
sub ulam {
my($n) = @_;
state %u = (1 => 1, 2 => 1);
state @ulams = <0 1 2>; # 0 a placeholder to shift indexing up one
return $ulams[$n] if $ulams[$n];
$n++;
my $i = 3;
while () {
my $count = 0;
$u{ $i - $ulams[$_] }
and $ulams[$_] != $i - $ulams[$_]
and $count++ > 2
and last
for 0..$#ulams;
$count == 2
and push(@ulams,$i)
and $u{$i} = 1
and @ulams == $n
and last;
$i++;
}
$ulams[$n-1];
}
printf "The %dth Ulam number is: %d\n", 10**$_, ulam(10**$_) for 1..4;</lang>
{{out}}
<pre>The 10th Ulam number is: 18
The 100th Ulam number is: 690
The 1000th Ulam number is: 12294
The 10000th Ulam number is: 132788
The 10000th Ulam number is: 132788</pre>
=={{header|Phix}}==
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