OFFSET
1,3
COMMENTS
a(24) > 2*10^5. - Robert Price, Sep 17 2015
LINKS
Makoto Kamada, Prime numbers of the form 600...007.
Sabin Tabirca and Kieran Reynolds, Lacunary Prime Numbers.
FORMULA
a(n) = A101518(n-1) + 1 for n>1. - L. Edson Jeffery, Nov 28 2013
MATHEMATICA
Do[ If[ PrimeQ[6*10^n + 7], Print[n]], {n, 0, 10000}]
PROG
(PARI) is(n)=ispseudoprime(6*10^n+7) \\ Charles R Greathouse IV, Jun 12 2017
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Robert G. Wilson v, Jan 18 2005
EXTENSIONS
a(19)-a(23) from Kamada link by Ray Chandler, Jan 04 2011
Inserted a(1)=0 by Robert Price, Sep 17 2015
STATUS
approved