OFFSET
1,1
EXAMPLE
a(1)=4 because 4=2*2=(5-3)*(5-3) where 2,3,5 and 5-3 are all prime, a(2)=6 because 6=2*3=(5-3)*(5-2) where 2,3,5,5-3 and 5-2 are all prime.
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, May 26 2010
EXTENSIONS
Extended beyond 478 by R. J. Mathar, May 28 2010
STATUS
approved