yes, the decades =1 (mod 3) contain about twice as much primes as the

others, i.e. about half of the primes.

Prime sieving "wheels" do commonly use the fact that primes >5 must equal

1,7,11,13, 17,19, 23, 29 (mod 30)

and they are roughly equally distributed among these 8 possible residues

of which 4 are in the decades you mention.

Maximilian

On Wed, Dec 29, 2010 at 12:36 AM,

rupert.wood@...
<

rupert.weather@...> wrote:

> I suspect this has been addressed somewhere. But here goes, anyway.

>

> In asymptotic (ratio) terms, are the decades 10-19, 40-49, 70-79, ... (which of course have no 3-divisors in the odd numbers except "at 5") any more likely to contain more primes than the other decades? I would guess that this is not so.

>