The clue gives us a series of hex numbers - 7C2BAC1D, 1CC28A903, 2AC30BE38, 52726803C, BF1D1DF06.
The key is name "The Audubon Key", which is a reference to birds. We also have "Watch the skies" and "small azure bird". that leads us to Twitter. If do a hashtag search (e.g. #7C2BAC1D) we find there is aTwitter accounts with a post with the hex numbers from our clue.
We search the other hex hashtags and we find an account for each.
Each Twitter account has a puzzle piece for its profile photo. Cool relates back to the clue. Now we have a puzzle piece for each of the hex numbers given in the clue.
We assume the rest of the puzzle pieces are on Twitter somewhere. What are their hashtags so we can find them?
Back to the hex numbers...
We notice that the first hex number is one character less than the others. Is there something special about it? Why yes there is !
The first block of the Bitcoin blockchain has a "Nonce" of 2083236893 which is decimal for the hex value 7C2BAC1D. The first block of Bitcoin is also called the Genesis Block and a lot of special meaning.
A Nonce is a 32 bit (4 byte) number that is adjusted by Bitcoin miners until the Hash of the block meets a certain specification. It will take many tries and lots of computer power to find the proper Nonce for a given Bitcoin block. This is what Bitcoin mining is all about. The first miner that solves the Nonce/Hash for a new Bitcoin block gets a reward in Bitcoin. Back to our treasure hunt...
So we know the puzzle has something to do with Bitcoin blockchain, Nonces and converting between hex and decimal numbers. Next we convert our hex numbers into decimal. A calculator on your phone/computer, or online tool can do that easily.
We notice that the decimal numbers are in increasing order,. That is a good sign. That could mean a sequence of some sort.
So... what does the next block in the Bitcoin blockchain look like? We can browse the Bitcoin blockchain here www.blockchain.com. Click the search icon at the top and enter "0" to see the Genesis Block.
Now use the search to find Block #1. We find a Nonce of 2573394689. Doesn't match any of our numbers above. We do find that the decimal value of the 2nd hex number in the clue is 3 times this Nonce though.... We are on to something ! We keeping going in the blockchain for blocks 0, 1, 2, 3, and 4. We find that the Nonce of each of these blocks is can be divided into the corresponding decimal number evently to create an integer.
|#||Hex||Decimal||Block #||Nonce||Dec / Nonce =|
Now we have a series of numbers - 1, 3, 7, 12, 18. A Google search finds that these numbers are part of a Hofstadter Figure-Figure sequence. This location gives us the first 53 numbers of this sequence.
1, 3, 7, 12, 18, 26, 35, 45, 56, 69, 83, 98, 114, 131, 150, 170, 191, 213, 236, 260, 285, 312, 340, 369, 399, 430, 462, 495, 529, 565, 602, 640, 679, 719, 760, 802, 845, 889, 935, 982, 1030, 1079, 1129, 1180, 1232, 1285, 1339, 1394, 1451, 1509, 1568, 1628, 1689
Does the next sequence work to find us a Twitter account with a puzzle piece? Bitcoin block #5 has a Nonce of 2011431709. Multiplied by the next Hofstadter number of 26 is 52297224434. Converted to hex is C2D2850F2. Search for a hashtag on Twitter - we find an account www.twitter.com/Carlos37002270. This is working !!! Here are the next 5 which all find us Twitter accounts with puzzle pieces.
|Block #||Nonce||Hofstadter||New Decimal||New Hex||Twitter Account|
We've confirmed the series is working. We do this for the first 50 Bitcoin blocks and we get a Twitter account for each. The Nonce * Hofstadter => Hex does find a Twitter account. We now have 40 puzzle pieces to assemble !
Here is a spreadsheet with all the details of how you get to the 50 Twitter accounts.
Assemble the puzzle pieces and you get the picture of a soda can shown in Clue #2