OFFSET
1,1
EXAMPLE
The composite c=4 of A002808 addresses prime(4) = 7 and the concatenation 47 is a prime, which adds 7 to the sequence.
The composite c=6 addresses prime(6)=13 and the concatenation 613 is prime which adds 13 to the sequence.
CROSSREFS
KEYWORD
nonn,base,less
AUTHOR
Juri-Stepan Gerasimov, Jan 19 2009
EXTENSIONS
Edited and extended beyond 61 by R. J. Mathar, May 05 2010
STATUS
approved