A103397 Semiprimes in A103377.

4, 9, 15, 21, 33, 38, 58, 65, 86, 106, 121, 129, 265, 511, 8114, 8193, 16307, 16853, 17855, 19857, 31298, 68037, 104739, 124205, 131209, 134149, 140457, 152849, 252914, 259918, 265358, 274606, 417527, 2498871, 5291863, 8424051, 8743821

Offset: 1

Author

Jonathan Vos Post, Feb 15 2005

Keywords

• easy
• nonn

Examples

			2071468241 is an element of A103377 and 2071468241= 17 * 121851073 which shows that it is a semiprime.
		

Crossrefs

Cf. A001358, A000931, A079398, A103372-103381, A103377, A103397.

Programs

Mathematica

SemiprimeQ[n_]:=Plus@@FactorInteger[n][[All, 2]]?2; Clear[a]; k=9; Do[a[n]=1, {n, k+1}]; a[n_]:=a[n]=a[n-k]+a[n-k-1]; A103377=Array[a, 100] A103387=Union[Select[Array[a, 1000], PrimeQ]] A103397=Union[Select[Array[a, 300], SemiprimeQ]] N[Solve[x^10 - x - 1 == 0, x], 111][[2]]

Formula

Intersection of A103377 with A001358.