OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..28
Eric Weisstein's World of Mathematics, Semiprime.
Eric Weisstein's World of Mathematics, Tribonacci Number.
MATHEMATICA
Select[LinearRecurrence[{1, 1, 1}, {0, 1, 1}, 150], PrimeOmega[#]==2&] (* Harvey P. Dale, Oct 16 2012 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Jonathan Vos Post and Ray Chandler, Dec 26 2004
STATUS
approved