Regular Expression for Serial Number

I'm trying to create a regex pattern a simple regular expression that match for a serial number contains space, hyphen and alphanumeric:
See below:  
Serial numbers with these following numbers:   20 4442-23 ,     42 4567-23AA   ,  56 0997 
for example:
"if regexp.match (20 4442-23) then button is disabled"
"if regexp.match (42 4567-23AA) then button is disabled"
"if regexp.match (56 0997) then button is disabled"

I tried one of these of them but none seems to work: 
(/^[-\sa-zA-Z]+$/,
^[\d]{2}[-\s]{1}[\d]{4}[-\s]{1}[\d]{2}$  
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