#R, 59 bytes
`for`(x,utf8ToInt(scan(,'')),cat(c(rep(';',x),'#'),sep=''))
reads from stdin. Loops through the ascii values of the input, replicating ';' that many times, appending a '#', and printing.59 56 bytes
for(x in utf8ToInt(scan(,'')))cat(rep(';',x),'#',sep="")
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