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Semiprimes in A006054.
0

%I #15 Nov 07 2015 13:53:20

%S 25,183922,413269,2086561,268550439,77664004259,1286498670037058,

%T 835992504648428541,69918194872608910320341,157104757807495406675035,

%U 353011186440414668176111,13139449230370726052061293111

%N Semiprimes in A006054.

%t 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@# &]

%t Select[LinearRecurrence[{2,1,-1},{0,0,1},100],PrimeOmega[#]==2&] (* _Harvey P. Dale_, Aug 21 2013 *)

%Y Cf. A006054, A006053.

%K nonn

%O 1,1

%A _Roger L. Bagula_ and _Gary W. Adamson_, Sep 15 2006

%E Edited by _N. J. A. Sloane_, Serp 17 2006

%E More terms from _Robert G. Wilson v_, Sep 18 2006