A344872 Semiprimes of the form 3m+2.

14, 26, 35, 38, 62, 65, 74, 77, 86, 95, 119, 122, 134, 143, 146, 155, 158, 161, 185, 194, 203, 206, 209, 215, 218, 221, 254, 278, 287, 299, 302, 305, 314, 323, 326, 329, 335, 341, 362, 365, 371, 377, 386, 395, 398, 407, 413, 422, 437, 446, 458, 473, 482, 485, 497

Offset

1,1

Comments

There are no square terms, as squares are congruent to 0 or 1 modulo 3.

Products of a prime of the form 3m+1 and a prime of the form 3m+2 (the former necessarily being of the form 6m+1).

Links

Table of n, a(n) for n=1..55.

Example

14 = 2 * 7 has 2 prime factors (counting repetitions) so is a semiprime, and 14 = 3*4 + 2, so has the form 3m+2. So 14 is in the sequence.

Mathematica

Select[Range[2, 500, 3], PrimeOmega@#==2&] (* Giorgos Kalogeropoulos, Jun 02 2021 *)

Prog

(PARI) isok(m) = bigomega(m) == 2 && m % 3 == 2;

Crossrefs

Intersection of A001358 and A016789.

Disjoint union of A108172 and A112772.

Complement within A001358 of A001748, A112771 and A112774.

Subsequence of A344703.

Sequence in context: A079702 A235688 A176274 * A240227 A191992 A082773

Adjacent sequences: A344869 A344870 A344871 * A344873 A344874 A344875

Keyword

nonn,easy

Author

Peter Munn, May 31 2021

Status

approved