[seqfan] Help with a calculation for A001097 (twin primes)
Bob Selcoe
rselcoe at entouchonline.net
Wed Nov 19 16:26:39 CET 2014
Hello Seqfans,
Is there a way to calculate the following limit as n approaches infinity? This will be helpful in a comment I intend to add to A001097 (twin primes)
Not sure about the most efficient or best way to notate, so here's what I'm asking:
For a(n)>1, let a(n) = A007310 (numbers congruent to 1 or 5 mod 6): 5, 7, 11, 13, 17, 19, 23, 25....
So a(1) = 5, a(2) = 7, a(3) = 11 etc.
Calculate 1/a(1) + 1/a(2)*(1 - 1/a(1)) + 1/a(3)*(1 - 1/a(1) - 1/a(2)) + 1/a(4)*(1 - 1/a(1) - 1/a(2) - 1/a(3))...
So 1/5 + 4/35 + 23/385 + 218/5005 +...
If this is not easily solved, could someone please run a program to get an approximation?
Thanks in advance!
Cheers,
Bob Selcoe
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