login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A209328 Decimal expansion of the sum of the inverse twin prime products. 1
1, 0, 7, 9, 8, 3, 9, 7, 4, 9, 5 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Summation up to the lesser prime(100000) gives 0.1079839703839.., summation up to the lesser prime(5000000) gives 0.10798397490956.. and summation up to the lesser prime(100000000) gives 0.107983974949..

The constant splits Brun's constant B=A065421 into two portions: define L=sum_{n>=1} 1/A001359(n) and U=sum_{n>=1} 1/A006512(n). Then B=U+L and this constant here = (L-U)/2. This leads to the estimates L=1.059064 and U=0.843096. - R. J. Mathar, Feb 05 2013

LINKS

Table of n, a(n) for n=0..10.

EXAMPLE

0.10798397495... =1/(3*5) + 1/(5*7) + 1/(11*13) + .. = sum_{n>=1} 1/A037074(n).

CROSSREFS

Sequence in context: A182688 A256924 A259069 * A228049 A154943 A126041

Adjacent sequences:  A209325 A209326 A209327 * A209329 A209330 A209331

KEYWORD

nonn,cons,more

AUTHOR

R. J. Mathar, Jan 19 2013

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 21 19:02 EST 2020. Contains 332109 sequences. (Running on oeis4.)