It is truly difficult for computers generate a true randomness. The less of a pattern that can be discerned, more entropy it contains.
Computer cryptography experts have become well versed with increasing the entropy of their encryptions. Steve Gibson for example has, in conjunction with feedback from the cryptography community, created a way to generate ultra-high security passwords that uses
Rijndael (AES) block encryption of never-repeating counter values in CBC mode
Despite the quote, the page make for a very good read.
Then for more fun there are Perfect Paper Passwords