Where does the 6^16 come from? There are only 16.7 million 24-bit RGB triples; naively, if you're treating 3-hexit and 6-hexit colours separately, that'd be 16,781,312 distinct pages. What am I missing?
One hex digit (0-F) is four bits. Six hex digits is (46) 24 bits. 24 bits is (2^24) 16.7 million combinations.
It is also legal to use three-digit colors in CSS, where (e.g.) #28d expands to #2288dd. In that context there are (43) 12 bits expressing (2^12) 4,096 colors. None of the three-digit codes from this group produce the same URL in the previous group, although all of the colors drawn on the screen are the same. For OP's purposes, these URLs are added to the others.
If one were to want to blow it up further, it's also legal to have an eight-digit hex code, where the rightmost two digits encode 256 possible levels of transparency for each color. That produces ~4 billion combinations.
Welp, you got me scrolling your HN thread to see where the "two-trillion-something" number came from. Between this and your experiment site, you have a knack for drawing attention.
If you think 3 positions, each 0-1, gives 3^2 options, then please show us the 9th three-bit number.
Even simpler is the case of 1 position that is 0-1. Does that give 1^2 or 2^1 options?
You are missing something. How many two-digit decimal numbers are there from 00 to 99? Obviously 99+1 = 100: 10 options for the first digit times 10 options for the second digit; 10 in the form 0X, 10 in the form 1X, etc. up to 9X, a total of 10 * 10 = 10^2.
So how many 6-digit hexadecimal numbers from 0x000000 to 0xffffff? 0xffffff+1 = 16777216 = 16^6. 16 options for the first digit, times 16 options for the second digit, times 16 for the 3rd, times 16 for the 4th, times 16 for the 5th, times 16 for the 6th is 16^6. Or go to bytes: 3 bytes, each with 256 possible values is 256^3 = (16^2)^3 = 16^6. Or bits: 2^24 = (2^4)^6 = 16^6.
It's also pretty trivial to just count them. Run this in your browser console:
