Talk:Palindromic prime

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[edit] Density of palindromic primes

The following seems obvious to me, but I can't think of a good source.

The density of palindromic primes, among numbers n with an odd number of digits, is conjectured to be asymtotically

{\ln n}^{-2}\prod_{p|{b^2-1}}{(1 - 1/p)}^{-1}

—The preceding unsigned comment was added by Arthur Rubin (talk • contribs) .

That looks familiar. A very similar formula might appear in Ribenboim's prime Guiness. I'll post tomorrow on this. PrimeFan 22:59, 5 July 2006 (UTC)
I was mistaken, it's not in Ribenboim's book. I looked at Mathworld, which quotes Banks (2004):

P(x) ~ O({{N(x) ln ln ln x} \over {ln ln x}})

Next I looked at the article on palindromic primes by Ondrejka and Dubner in J. Recr. Math. 26(4), which has plenty of concrete numbers but no formulas. PrimeFan 23:01, 6 July 2006 (UTC)