OFFSET
1,1
PROG
(PARI) isok(k) = (prime(k) + prime(k+4)) == (prime(k+1) + prime(k+3)); \\ Michel Marcus, Sep 30 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Corrected by R. J. Mathar, Aug 06 2015
STATUS
approved