OFFSET
1,2
EXAMPLE
a(1)=1 because k=0=non-semiprime and 0+4=4=semiprime; a(2)=3 because k=2=non-semiprime and 2+4=6=semiprime, 2+8=10=semiprime, 2+12=14=semiprime; a(3)=1 because k=5=non-semiprime and 5+4=9=semiprime.
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladislav-Stepan Malakovsky & Juri-Stepan Gerasimov, Aug 01 2010
STATUS
approved