Thanks, this is interesting. As far as writing a program to extract primes from that number, how could you without including a prime test in the program? You'd think Erdos and friends would have made it easier by bothering to encode word boundaries - say with a prefix free code[1] :) - 01 for a word boundary, 00 for a true 0:

0.0120130150170111011301170119012301290131013701410143... (no encoded zeros in this example.)

Then you wouldn't have to brute-force word boundaries... You could also put the ordinality of the prime number between 08...09 tags, then you could know exactly whether you're looking at the millionth prime or the million and second one.

But yeah other than not encoding boundaries you are right, it's quite akin to the real number you provided. I like your explanation - thanks.

EDIT: also, as I show above, the program to get a prime back out can seem complicated. What's remarkable about mill's constant is that the program is simple: just raise Mill's constant to 3^n (and apply the floor function). seems so simple. What's remarkable is not just that such a constant exists - that will give you a prime for any n - but that there is a smallest such constant and we already know it:

1.3063778838630806904686144926...

I find that remarkable. raise that to any 3^n and you get a prime and change. wow.

EDIT2: Your argument also didn't address one thing I'm curious about - why a similar number can't exist for 2^n instead of 3^n... thanks for any thoughts.

[1] http://en.wikipedia.org/wiki/Prefix_code