OFFSET
1,2
EXAMPLE
a(1)=1 because prime(1)+1=3=prime; a(2)=2 because prime(2)+1=4=semiprime; a(3)=3 because prime(3)+1=6=semiprime; a(4)=6 because prime(6)+1=14=semiprime.
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Mar 29 2010
EXTENSIONS
Extended by Ray Chandler, Apr 06 2010
STATUS
approved