A103396 Semiprimes in A103376.

4, 9, 15, 21, 33, 38, 58, 65, 86, 106, 121, 129, 265, 511, 2038, 2059, 4097, 4174, 7894, 16021, 19857, 31313, 32419, 33238, 37711, 116197, 196609, 220937, 262978, 273926, 955743, 34826059, 64229819, 67835071, 77834009, 497049562, 4370946037

Offset: 1

Author

Jonathan Vos Post, Feb 05 2005

Keywords

• nonn
• easy

Comments

Intersection of A103376 with A001358.

Crossrefs

Cf. A001358, A103376, A103386, A103392-A103401.

Programs

Mathematica

SemiprimeQ[n_] := Plus @@ FactorInteger[n][[All, 2]] == 2; k = 8; Do[a[n] = 1, {n, k + 1}]; a[n_] := a[n] = a[n - k] + a[n - k - 1]; Union[Select[Array[a, 280], SemiprimeQ]]
Union[Select[LinearRecurrence[{0,0,0,0,0,0,0,1,1},{1,1,1,1,1,1,1,1,1},300],PrimeOmega[#]==2&]] (* Harvey P. Dale, May 07 2015 *)

Extensions

Edited and extended by Ray Chandler, Feb 10 2005