[0-9_]*[a-zA-Z][a-zA-Z0-9_]*

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So to check if an entire string matches one of your sequences, 

if ($str =~ /^[0-9_]*[a-zA-Z][a-zA-Z0-9_]*\z/) {
   ...
}

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In reply to Re: Looking for a regular expression for the following pattern. by ikegami
in thread Looking for a regular expression for the following pattern. by skooma

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