A122500 - OEIS

A122500

Semiprimes in A006054.

25, 183922, 413269, 2086561, 268550439, 77664004259, 1286498670037058, 835992504648428541, 69918194872608910320341, 157104757807495406675035, 353011186440414668176111, 13139449230370726052061293111

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..12.

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

Cf. A006054, A006053.

Sequence in context: A211600 A068737 A151649 * A347812 A251362 A196520

Adjacent sequences: A122497 A122498 A122499 * A122501 A122502 A122503

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