OFFSET
1,1
EXAMPLE
a(1)=10 because 10-4=6, 10 and 10+4=14 are all twin semiprimes.
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Aug 12 2010
EXTENSIONS
Corrected (299, 411 etc inserted) by R. J. Mathar, Aug 13 2010
STATUS
approved