Where is my hammer?

sub isPrime($) {
    $n=pop;
    1^(1x$n--)=~/^(1{2,$n})\1+$/;
}

[download]

With n>2

Just for fun as a contrib to https://github.com/fxn/math-with-regexps/blob/master/one-liners.sh (fxn).

Update, thanks to ambrus's reply: Re^2: is it prime?

sub isPrime($) {
   (1x pop)!~/^(11+)\1+$/
}

[download]

In reply to Re: is it prime? by brx
in thread is it prime? by Anonymous Monk

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