A142862 Semiprimes n (A001358) for which A000001(n) is 1.

15, 33, 35, 51, 65, 69, 77, 85, 87, 91, 95, 115, 119, 123, 133, 141, 143, 145, 159, 161, 177, 185, 187, 209, 213, 215, 217, 221, 235, 247, 249, 259, 265, 267, 287, 295, 299, 303, 319, 321, 323, 329, 335, 339, 341, 365, 371, 377, 391, 393, 395, 403, 407, 411

Offset: 1

Author

N. J. A. Sloane, Oct 03 2008

Keywords

• nonn

Comments

Semiprimes pq with pT. D. Noe, Oct 08 2008

References

• D. S. Dummit and R. M. Foote, Abstract Algebra, Wiley, 3rd Edition, 2003, page 135.

Links

• T. D. Noe, Table of n, a(n) for n=1..1000
• John H. Conway, Heiko Dietrich and E. A. O'Brien, Counting groups: gnus, moas and other exotica.

Crossrefs

Cf. A050384, A003277. [Franklin T. Adams-Watters, Feb 27 2009]

Programs

Mathematica

Select[Select[Range[1000],FactorInteger[#][[All, 2]] == {1, 1} &], !
Divisible[FactorInteger[#][[2, 1]] - 1, FactorInteger[#][[1, 1]]] &] (* Geoffrey Critzer, Nov 07 2015 *)

Extensions

More terms from R. J. Mathar, Oct 04 2008