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%I #9 Apr 22 2015 10:33:44
%S 4,9,15,21,33,38,58,86,106,122,485,905,1939,4163,6697,12381,14473,
%T 22889,107833,170769,370729,687634,804106,1093762,1276259,2767999,
%U 11140379,15186449,210634829,286937249,391048473,532793518,725995178,847539571
%N Semiprimes in A103372.
%C Intersection of A103372 with A001358.
%e 276799 is an element of this sequence because A103372(99) = 276799 and 276799 is semiprime because 276799 = 31 * 8929 where both 31 and 8929 are primes.
%t SemiprimeQ[n_] := Plus @@ FactorInteger[n][[All, 2]] == 2; k = 4; Do[a[n] = 1, {n, k + 1}]; a[n_] := a[n] = a[n - k] + a[n - k - 1]; Union[Select[Array[a, 150], SemiprimeQ]]
%t Union[Select[LinearRecurrence[{0,0,0,1,1},{1,1,1,1,1},150],PrimeOmega[#] == 2&]] (* _Harvey P. Dale_, Apr 22 2015 *)
%Y Cf. A001358, A103372, A103382, A103393-A103401.
%K nonn,easy
%O 1,1
%A _Jonathan Vos Post_, Feb 03 2005
%E Edited, corrected and extended by _Ray Chandler_ and _Robert G. Wilson v_, Feb 06 2005