They did seem to suggest that perhaps the numbers are coded letters.
Perhaps it's not a "sequence of numbers" but rather a "sequence of letters represented with numbers".
@zedvictor:
Even Mr A our resident philosophical scholar and wordsmith is baffled by something so simple.
"Mr. A" isn't "baffled." "Mr. A" refused to guess. 3RU7AL was right. The numbers were coded letters.
A (1) B (2) C (3) D (4) E (5) F (6) G (7) H (8) I (9) J (10) K (11) L (12) M (13) N (14) O (15) P (16) Q (17) R (18) S (19) T (20) U (21) V (22) W (23) X (24) Y (25) Z (26.)
The fact that you insist each numbers' value Is necessarily less than "27" is tacit admission that you're referring to a series of possible solutions between 0 and 26, despite the fact that 0 doesn't correspond with any letter of the alphabet. (It's also important to note that by just looking at the numbers as you presented them, they are all necessarily less than "∞". So, there's no reason one would be prone to identifying that the parameter is "less than 27" (and greater than or equal to "1".) One would still have to guess. So on to your "puzzle":
1, 2, 5, 20, 1, 4, 5, 20, ?
If each number corresponds with a letter of the English Alphabet, then this series of numbers would be:
"ABETADET?"
This is an anagram for:
"DEBATEA?T"
The mystery letter is "R":
"DEBATEART"
and "R" corresponds with the number "18." (It's just a coincidence that 18 is the sum total of the series of numbers excluding the 20's.)
So the series of numbers should've really looked like this:
"4, 5, 2, 1, 20, 5, 1, 18, 20."
Anyway, zedvictor, this is still a guessing game. Identifying that these random set of numbers were less than "27" would've been no less a shot in the dark than identifying that these random set of numbers were less than "24" (Greek Alphabet) or "71" (Japanese Hiragana.) And the fact that it has to be greater than or equal to "1" escaped your mention. Once again, the parameters were known to just you--making it a guessing game.
@3RU7AL:
And yet, it was shockingly popular.
Yeah, this received more attention than it should have.