OFFSET
1,6
LINKS
FUNG Cheok Yin, Table of n, a(n) for n = 1..10000
PROG
(PARI) a(n) = primepi(7*n) - primepi(6*n); \\ Michel Marcus, Jul 08 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
FUNG Cheok Yin, Jul 07 2017
STATUS
approved