creating bitcoin addresses seams not random - why?

[TomCoin]

well since i am a new member i can only ask in newbee forum.

i have written a tiny piece oft software which uses JSON RPC to create new bitcoin addresses in my wallet. i was trying to find a bitcoin address which stars with "1Tom.....". Just for fun and playing around with bitcoind.

After the software created A LOT bitcoin addresses it seems that some addresse occur more often than others.

F.E.

i found 7 addresses that startet with "1To" (3 chars)
i found 24 addresses that startet with "1pwc" (4 chars)
(not case sensitive)

then i deleted the wallet and startet again. same result. (4 times)

Why is that?

[nimda]

By "same result" you mean you got the same addresses after deleting wallet.dat? That is a Bad Thing. What OS are you on?

[TomCoin]

no i did not get the same addresses after deleting the wallet.

but i seems that there are some starters like "1pw..." or "1bm..." are by far more often occuring than others like "1To". like 40 times more often.

[PenAndPaper]

How many addresses you created in total? Probably it's just variance 

[DeathAndTaxes]

Bitcoin ADDRESSES are not PUBLIC KEYS.  Bitcoin ADDRESSES are a versioned and checksummed PUBLIC KEY encoded in base 58.  Due to the method of encoding in base 58 addresses aren't randomly distributed.

If you converted those addresses to their raw public keys they will be randomly distributed.

[TomCoin]

well its a java tool running a endless while(true) since 6 hours. i cannot tell exactly how much

but thanks DeathAndTaxes, that explains it.

[PenAndPaper]

Bitcoin ADDRESSES are not PUBLIC KEYS.  Bitcoin ADDRESSES are a versioned and checksummed PUBLIC KEY encoded in base 58.  Due to the method of encoding in base 58 addresses aren't randomly distributed.

If you converted those addresses to their raw public keys they will be randomly distributed.

How are they distributed then if not randomly 
Maybe you mean that they don't follow a uniform distribution, but then what distribution they follow?

[DeathAndTaxes]

They are biased towards certain prefxes due to the effect of the version code.  If you wanted you could graph the distribution, I have never really cared enough I just remember from the vanityaddress thread this makes certain addresses harder to find. 

Just to be clear there is no security implication.  Public keys are randomly distributed.  Addresses are simply encoded public keys.