OFFSET
1,2
LINKS
G. Niklasch, Some number theoretical constants: 1000-digit values [Cached copy]
FORMULA
Equals Sum_{k>=1} A003557(k)/k^3. - Amiram Eldar, Jan 25 2024
EXAMPLE
1.2312911488886035627747876512720337...
MATHEMATICA
$MaxExtraPrecision = 600; digits = 99; terms = 600; P[n_] := PrimeZetaP[n]; LR = Join[{0, 0, 0}, LinearRecurrence[{0, 2, -1, -1, 1}, {3, 0, 5, -3, 7}, terms + 10]]; r[n_Integer] := LR[[n]]; Exp[NSum[r[n]*P[n - 1]/(n - 1), {n, 3, terms}, NSumTerms -> terms, WorkingPrecision -> digits + 10]] // RealDigits[#, 10, digits]& // First (* Jean-François Alcover, Apr 18 2016 *)
PROG
(PARI) prodeulerrat(1 + 1/(p*(p^2-1))) \\ Amiram Eldar, Mar 17 2021
CROSSREFS
KEYWORD
cons,nonn
AUTHOR
N. J. A. Sloane, Nov 19 2001
STATUS
approved