OFFSET
1,2
EXAMPLE
a(1)=0 because there is no twin prime smaller than 2.
a(2)= 4 counts the numbers 3, 5, 11, and 17 all smaller than 23.
a(3) = 5 counts the numbers 3, 5, 11, 17, and 29 all smaller than 37.
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Jul 01 2009
EXTENSIONS
Entried checked by R. J. Mathar, Sep 23 2009
STATUS
approved