[seqfan] Re: Call for more digits of 1/(3*5) + 1/(5*7) + 1/(7*11)

[Hans Havermann]

The actual contribution from 11-digit primes turned out to be 3.78852571*10^-12. Emboldened by the proximity of this to my guess, I derived extrapolated contributions from 12- to 17-digit primes and added them to my sum for up to and including 1/(largest-11-digit-prime*smallest-12-digit-prime). This conservatively yields yet another three terms of the sequence for a total now of 15 digits.

On Jan 22, 2013, at 10:38 PM, Hans Havermann <gladhobo at teksavvy.com> wrote:

> For what it's worth, I've added three digits to the 9 that were in A209329. I had a value of 0.13442650968756437 for the sum up to and including 1/(largest-10-digit-prime*smallest-11-digit-prime). The contributions from 5- to 10-digit primes were:
> 
> 5     9.0085*10^-6
> 6     7.3442*10^-7
> 7     6.1915*10^-8
> 8     5.3439*10^-9
> 9     4.7004*10^-10
> 10    4.1954*10^-11
> 
> From this I guessed:
> 
> 11   ~3.786*10^-12
> 12     ~3.5*10^-13
> 
> giving the three extra digits.