OFFSET
1,1
EXAMPLE
4.6197768903303689380682119968437423840172825564412923389842082329...
MATHEMATICA
semiPrimeQ[n_] := Plus @@ Last /@ FactorInteger@n == 2; lst = Select[Range@ 400, semiPrimeQ@ # &]; First@ RealDigits@ N[ Fold[ Last@ #2 + First@ #2/#1 &, 4, Partition[Reverse@ lst, 2]], 111] (* Robert G. Wilson v *)
CROSSREFS
KEYWORD
cons,nonn
AUTHOR
Jonathan Vos Post & Robert G. Wilson v, Sep 08 2007
STATUS
approved