Barban's constant is defined as
 |  | ![product_(p)[1+(3p^2-1)/(p(p+1)(p^2-1))]](/images/equations/BarbansConstant/Inline3.svg) |
(1)
|
 |  |  |
(2)
|
(OEIS A175640), where the product is over the primes 
.
Barban's Constant
See also
Artin's Constant, Feller-Tornier Constant, Heath-Brown-Moroz Constant, Murata's Constant, Prime Products, Quadratic Class Number Constant, Sarnak's Constant, Taniguchi's Constant, Twin Primes ConstantExplore with Wolfram|Alpha
References
Barban, M. B. "The Large Sieve Method and Its Application to Number Theory." Uspehi Mat. Nauk 21, 51-102, 1966.Finch, S. "Class Number Theory." http://algo.inria.fr/csolve/clss.pdf. May 6, 2005.Sloane, N. J. A. Sequence A175640 in "The On-Line Encyclopedia of Integer Sequences."Cite this as:
Weisstein, Eric W. "Barban's Constant." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/BarbansConstant.html