OFFSET
1,2
COMMENTS
This is also the solution x to Sum_{c composite}(1/c^x) = 1.
LINKS
Hiroaki Yamanouchi, Table of n, a(n) for n = 1..100
EXAMPLE
1.4257...
MATHEMATICA
x /. FindRoot[Zeta[x] - PrimeZetaP[x] == 2, {x, 3/2}, WorkingPrecision -> 100] // RealDigits // First (* Jean-François Alcover, May 07 2021 *)
PROG
(PARI) solve(x=1.1, 2, zeta(x) - sumeulerrat(1/p, x) - 2) \\ Michel Marcus, May 07 2021
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Matthew Campbell, Oct 06 2015
EXTENSIONS
a(6) corrected and a(7)-a(87) added by Hiroaki Yamanouchi, Nov 12 2015
STATUS
approved