A103004 Numbers n such that 5*10^n + 9 is prime.

1, 2, 3, 5, 8, 20, 29, 86, 283, 757, 1199, 2473, 2733, 24853, 39629, 53492, 71237, 72302, 81653, 167510

Offset

1,2

Comments

a(21) > 2*10^5. - Robert Price, Aug 10 2015

Links

Table of n, a(n) for n=1..20.

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

Cf. A101569.

Sequence in context: A049908 A334535 A135568 * A102016 A002363 A041457

Adjacent sequences: A103001 A103002 A103003 * A103005 A103006 A103007

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