OFFSET
1,1
COMMENTS
a(29) >= 1091. A000073(1091) is a 288-digit composite number with unknown factorization. Other possible terms are 1390, 1630, 2034, 2131, 2339, ... - Tyler Busby, Feb 09 2023
LINKS
Eric Weisstein's World of Mathematics, Semiprime
MATHEMATICA
Flatten[Position[LinearRecurrence[{1, 1, 1}, {1, 1, 2}, 100], _?(PrimeOmega[ #]==2&)]]+1 (* This generates the first 12 terms of the sequence. To generate more, increase 100 to a higher number, but it will take increasingly long to run. *) (* Harvey P. Dale, May 31 2013 *)
CROSSREFS
KEYWORD
nonn,more,less
AUTHOR
Jonathan Vos Post and Ray Chandler, Dec 26 2004
EXTENSIONS
More terms from David Wasserman, Apr 03 2008
STATUS
approved