OFFSET
1,1
MATHEMATICA
semiPrimeQ[n_Integer] := Plus @@ Last /@ FactorInteger[n] == 2; s = CoefficientList[ Series[x/(x^3 - x^2 - 2*x + 1), {x, 0, 100}], x]; Select[s, SemiprimeQ@# &]
Select[LinearRecurrence[{2, 1, -1}, {0, 0, 1}, 100], PrimeOmega[#]==2&] (* Harvey P. Dale, Aug 21 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Roger L. Bagula and Gary W. Adamson, Sep 15 2006
EXTENSIONS
Edited by N. J. A. Sloane, Serp 17 2006
More terms from Robert G. Wilson v, Sep 18 2006
STATUS
approved