Find numbers n in base 2 where n is prime and all it's digits are 1

Find numbers n in base 2 where n is prime and all it's digits are 1
Let 1 < n < 10000

Find numbers n in base 2 where n is prime and all it's digits are 1 is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Task

Ring

<lang ring> load "stdlib.ring"

num = 0 limit = 6 decList = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15] baseList = ["0","1","2","3","4","5","6","7","8","9","A","B","C","D","E","F"]

see "working..." + nl see "the first 5 elements of sequence are:" + nl

for n = 1 to 10000

   if isprime(n)
      flag = 1
      bn = decimaltobase(n,2)
      for m = 1 to len(bn)
          if not(bn[m] = "1") 
             flag = 0
             exit
          ok
      next
      if flag = 1
         num = num + 1
         if num < limit
            see "" + num + ". " + "number = " + n + " in base 2 = " + bn + nl
         ok
      ok
   ok

next

see "done..." + nl

func decimaltobase(nr,base)

    binList = [] 
    binary = 0
    remainder = 1
    while(nr != 0)
         remainder = nr % base
         ind = find(decList,remainder)
         rem = baseList[ind]
         add(binList,rem)
         nr = floor(nr/base) 
    end
    binlist = reverse(binList)
    binList = list2str(binList)
    binList = substr(binList,nl,"")  
    return binList

</lang>

Output:

working...
the first 5 elements of sequence are:
1. number = 3 in base 2 = 11
2. number = 7 in base 2 = 111
3. number = 31 in base 2 = 11111
4. number = 127 in base 2 = 1111111
5. number = 8191 in base 2 = 1111111111111
done...