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 A176073 Semiprimes of the form 3^k + 2^k + k + 1. 1
 39, 2323, 6826, 179207, 14381691, 129271253, 617675543767627, 5559069156490149, 450284043329950873, 174449211045148976090134531, 5474401089420370497804607762216590113 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..14 EXAMPLE 39 = 3*13 = 3^3 + 2^3 + 3 + 1. MATHEMATICA f[n_] := Last/@FactorInteger[n] == {1, 1}; Select[Array[3^# + 2^# + # + 1&, 90], f[#] &] Select[Table[3^n + 2^n + n + 1, {n, 130}], PrimeOmega[#] == 2&] (* Vincenzo Librandi, Sep 21 2012 *) PROG (PARI) for(n=1, 1e2, if(bigomega(t=3^n+2^n+n+1)==2, print1(t", "))) \\ Charles R Greathouse IV, Apr 16 2012 (Magma) IsSemiprime:=func; [s: n in [2..130] | IsSemiprime(s) where s is 3^n + 2^n + n + 1]; // Vincenzo Librandi, Sep 21 2012 CROSSREFS Sequence in context: A139191 A319490 A327589 * A145619 A027490 A323688 Adjacent sequences: A176070 A176071 A176072 * A176074 A176075 A176076 KEYWORD nonn,easy AUTHOR Vladimir Joseph Stephan Orlovsky, Apr 07 2010 STATUS approved

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Last modified September 12 22:20 EDT 2024. Contains 375855 sequences. (Running on oeis4.)