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.+
$*
^.$|^((.)+)(?=1円*$)(?<=..)(?<!^3円+(..+))(?!((?<-2>1円)+)(?(2)^)4円*$)
Try it online! Link includes test cases. Outputs 0 for a Guiga number, 1 if not. Explanation:
.+
$*
Convert n to unary.
^.$|
Special-case 1, as all of its prime factors satisfy the relation but it's not composite so it's excluded.
^((.)+)
Match an integer p=1円, but also as a count 2円, where...
(?=1円*$)
... p must be a factor of n, ...
(?<=..)
... p must be at least 2, ...
(?<!^3円+(..+))
... p must not have a nontrivial proper factor 3円, and...
(?!((?<-2>1円)+)(?(2)^)4円*$)
... n-p must not be divisible by p2, which is calculated by matching 1円 2円 times, and then captured, so that it can be easily repeated using 4円.
Neil
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