This site is supported by donations to The OEIS Foundation.

Annual Appeal: Please make a donation (tax deductible in USA) to keep the OEIS running. Over 5000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A065465 Decimal expansion of product(1 - 1/(p^2*(p+1))), p prime >= 2). 2
 8, 8, 1, 5, 1, 3, 8, 3, 9, 7, 2, 5, 1, 7, 0, 7, 7, 6, 9, 2, 8, 3, 9, 1, 8, 2, 2, 9, 0, 3, 2, 2, 7, 8, 4, 7, 1, 2, 9, 8, 6, 9, 2, 5, 7, 2, 0, 8, 0, 7, 6, 7, 3, 3, 6, 7, 0, 1, 6, 8, 5, 3, 5, 5, 4, 8, 6, 5, 7, 9, 0, 6, 3, 7, 9, 4, 1, 6, 9, 7, 4, 1, 0, 2, 2, 0, 4, 5, 5, 1, 7, 9, 7, 0, 2, 0, 9, 6 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS Eckford Cohen, Arithmetical functions associated with the unitary divisors of an integer, Math. Zeitschr. 74 (1960) 66-80. S. R. Finch, Class number theory, page 7. R. J. Mathar, Hardy-Littlewood constants embedded into infinite products..., arXiv:0903.2514 [math.NT], 2009-2011, Table 5, constant Q_1^(2). G. Niklasch, Some number theoretical constants: 1000-digit values [Cached copy] Simon Plouffe, Generalized expansions of real numbers, 2006 Eric Weisstein's World of Mathematics, Quadratic Class Number Constant Eric Weisstein's World of Mathematics, Prime Products FORMULA sum_{n>=1} phi(n)/(n*J(n)) = (this constant)*A013661 with phi()=A000010() and J() = A007434() [Cohen, Corollary 5.1.1], - R. J. Mathar, Apr 11 2011 EXAMPLE 0.88151383972517077692839182290... MATHEMATICA \$MaxExtraPrecision = 1000; digits = 98; terms = 1000; LR = Join[{0, 0, 0}, LinearRecurrence[{-2, -1, 1, 1}, {-3, 4, -5, 3}, terms+10]]; r[n_Integer] := LR[[n]]; Exp[NSum[r[n]*PrimeZetaP[n-1]/(n-1), {n, 4, terms}, NSumTerms -> terms, WorkingPrecision -> digits+10]] // RealDigits[#, 10, digits]& // First (* Jean-François Alcover, Apr 16 2016 *) CROSSREFS Cf. A078087. Sequence in context: A091648 A135707 A021923 * A265308 A199597 A197848 Adjacent sequences:  A065462 A065463 A065464 * A065466 A065467 A065468 KEYWORD cons,nonn AUTHOR N. J. A. Sloane, Nov 19 2001 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.