Here's a little sequence of letters & numbers arranged in a specific way. Without yet giving away anymore info other than the title, the tag and that this sequence is complete try replace the question marks.

D11010101Z, ━━━━, A1011101F, A111101U, A101100011L, A1-100001100G, ????????

  • $\begingroup$ I've been tearing my hair out for hours now and I can't make headway. Is it too early to ask for a small hint? $\endgroup$
    – Sciborg
    Commented Oct 10, 2020 at 22:18
  • $\begingroup$ @Sciborg I think Amos got this. I'll wait and see $\endgroup$ Commented Oct 11, 2020 at 8:57

1 Answer 1


Looks like


I got stuck on the 'order within an order'; thanks OP for the hint!

If one orders the seven continents alphabetically and within that orders their countries alphabetically, this sequence is the first country from each continent. (scrambled as described in a little bit)
Africa - Algeria
Antarctica - Antarctica, not a country I guess, so an M-dash
Asia - Afghanistan
Australia - Australia
Europe - Albania
N America - Antigua/Barbuda
and the missing entry, S America - Argentina
Each result is then scrambled as such:
Numeric country code converted to binary, nested within the 2 digit ISO code.
Argentina is country code 54=110110 binary, ISO Code 'AR' yields: A110110R

  • 2
    $\begingroup$ Do you mind explaining how you got to this? If you have figured out something it may be helpful to explain for others to work on. $\endgroup$
    – Sciborg
    Commented Oct 11, 2020 at 5:17
  • $\begingroup$ @Amos Zoellner You basically got it. rot13(gur svefg ragel yvrf va? gur frpbaq va? gur guveq, sbhegu rgp va? ...naq Jul?) $\endgroup$ Commented Oct 11, 2020 at 8:48
  • 1
    $\begingroup$ To reviewers: Obviously this answer needs to be explained, but it's not worth deleting, especially since the OP has said "You basically got it." $\endgroup$ Commented Oct 11, 2020 at 14:04
  • 2
    $\begingroup$ The explanation does need to be edited into the answer, though ... $\endgroup$
    – Glorfindel
    Commented Oct 11, 2020 at 15:40
  • 2
    $\begingroup$ Updated with explanation $\endgroup$
    – Amoz
    Commented Oct 11, 2020 at 21:06

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