Hi Steve,

Do you mean by that once you get the result only RANDBETWEEN function's value gets converted into static random number?

If this is the case, then as far as my knowledge, You can convert manually by pressing F9 key after selecting the highlighted part but once you hit enter you can't have function (RANDBETWEEN) with that formula. 
=IF(AND(B3="",C3="",D3=""),"",CONCATENATE("Student ",B3,"-",C3,"-",RANDBETWEEN(0,500000)))


Or You can convert the entire formula by performing CTRL+C-->PASTE SPECIAL-->VALUE

Waiting to hear from you.