A142863 Semiprimes n (A001358) for which A000001(n) is 2.

4, 6, 9, 10, 14, 21, 22, 25, 26, 34, 38, 39, 46, 49, 55, 57, 58, 62, 74, 82, 86, 93, 94, 106, 111, 118, 121, 122, 129, 134, 142, 146, 155, 158, 166, 169, 178, 183, 194, 201, 202, 203, 205, 206, 214, 218, 219, 226, 237, 253, 254, 262, 274, 278, 289, 291, 298, 301

Offset

1,1

Comments

Semiprimes p^2 or pq with p<q and gcd(p,q-1)=p. - T. D. Noe, Oct 08 2008

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. A000001, A001358.

Sequence in context: A193305 A084759 A054395 * A318990 A375182 A132435

Adjacent sequences: A142860 A142861 A142862 * A142864 A142865 A142866

Keyword

nonn

Author

N. J. A. Sloane, Oct 03 2008

Extensions

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

Status

approved