OFFSET
1,2
COMMENTS
a(21) > 2*10^5. - Robert Price, Aug 10 2015
LINKS
Makoto Kamada, Prime numbers of the form 500...009.
Sabin Tabirca and Kieran Reynolds, Lacunary Prime Numbers.
FORMULA
a(n) = A101569(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[5*10^n + 3], Print[n]], {n, 0, 10000}]
PROG
(PARI) is_ok(n)=isprime(5*10^n + 9);
first(m)=my(v=vector(m), t); for(i=1, m, while(!is_ok(t), t++; ); v[i]=t; t++); v; /* Anders Hellström, Aug 10 2015 */
CROSSREFS
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Jan 18 2005
EXTENSIONS
a(14)-a(19) from Kamada data by Robert Price, Dec 10 2010
a(20) from Robert Price, Aug 10 2015
STATUS
approved