sub e{    
    my @e=(1)x shift;
    my $f="%d.";
    local $|=1;
    for(1..@e*log(@e)/11){
        for(reverse(1..$#e)){
            $e[$_-1]+=$e[$_]/$_;
            $e[$_]=10000*($e[$_]%$_)
        }
        printf$f,$e[0];
        $e[0]=0;
        $f="%04d";
    }
}
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