in reply to undefined value as an ARRAY

You're probably running out of memory!

According to Wolfram/Alpha, 2**128! is 101040.11273643527576 and has 85070591730234615865843651857942052838 trailing zeros.

As such, it would require more memory than will ever exist to calculate.

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
RIP an inspiration; A true Folk's Guy

In Section Seekers of Perl Wisdom