Generating a list of random words in Excel, but no duplicates -

i'm trying generate words in column b list of given words in column a.

right code in excel vba this:

function gettext()     dim givenwords     givenwords = sheets(1).range(sheets(1).[a1], sheets(1).[a20])     gettext = a(application.randbetween(1, ubound(a)), 1) end function 

this generates word list have provided in a1:a20, i don't want duplicates.

gettext() run 15 times in column b b1:b15.

how can check duplicates in column b, or more efficiently, remove words temporarily list once has been used?

for example,

1. select range a1:a20
2. select 1 value randomly (e.g a5)
3. a5 in column b1
4. select range a1:a4 , a6:a20
5. select 1 value randomly (e.g a7)
6. a7 in column b2
7. repeat, etc.

this trickier thought. formula should used vertical array eg. select cells want output, press f2 type =gettext(a1:a20) , press ctrl+shift+enter

this means can select input words in worksheet, , output can upto long list of inputs, @ point you'll start getting #n/a errors.

function gettext(givenwords range)     dim item variant     dim list new collection     dim aoutput() variant     dim tempindex integer     dim x integer      redim aoutput(givenwords.count - 1) variant     each item in givenwords         list.add (item.value)     next     x = 0 givenwords.count - 1         tempindex = int(rnd() * list.count + 1)         aoutput(x) = list(tempindex)         list.remove tempindex     next      gettext = application.worksheetfunction.transpose(aoutput()) end function