OFFSET
1,1
EXAMPLE
a(1)=3 because (1st semiprime) - (-1)^(1st semiprime) = 4 - 1 = 3.
MATHEMATICA
#-(-1)^#&/@Select[Range[200], PrimeOmega[#]==2&] (* Harvey P. Dale, Nov 08 2012 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Apr 22 2010
EXTENSIONS
Entries checked by R. J. Mathar, Apr 27 2010
STATUS
approved