A085711 Numbers k such that sopfr(k) is a semiprime.

4, 8, 9, 14, 20, 21, 24, 25, 26, 27, 30, 32, 33, 36, 38, 44, 46, 49, 57, 62, 68, 69, 70, 74, 84, 85, 93, 94, 100, 102, 105, 106, 112, 116, 120, 121, 124, 125, 126, 128, 129, 133, 134, 135, 144, 145, 150, 152, 160, 162, 166, 169, 171, 174, 177, 178, 180, 182, 188

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

19770 = 2*3*5*659 is a term because 2+3+5+659 = 669 = 3*223.

Mathematica

seqQ[n_] := PrimeOmega[Plus @@ Times @@@ FactorInteger[n]] == 2; Select[Range[200], seqQ] (* Amiram Eldar, Dec 14 2019 *)

Crossrefs

Cf. A001358, A001414.

Sequence in context: A110087 A312830 A312831 * A182491 A281686 A122785

Adjacent sequences: A085708 A085709 A085710 * A085712 A085713 A085714

Keyword

easy,nonn

Author

Jason Earls, Jul 19 2003

Status

approved