login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A122500 Semiprimes in A006054. 0
25, 183922, 413269, 2086561, 268550439, 77664004259, 1286498670037058, 835992504648428541, 69918194872608910320341, 157104757807495406675035, 353011186440414668176111, 13139449230370726052061293111 (list; graph; refs; listen; history; text; internal format)
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 * A251362 A196520 A228536

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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 14 09:25 EDT 2019. Contains 327995 sequences. (Running on oeis4.)