A174175 Numbers n such that 10^n + 2*n - 1 is prime.

1, 2, 4, 10, 20, 35, 91, 112, 116, 325, 367, 674, 2440, 14099, 38315, 47989

Offset

1,2

Comments

a(17) > 10^5. - Robert Price, Mar 24 2015

Links

Table of n, a(n) for n=1..16.

Mathematica

Select[Range[5000], PrimeQ[(10^# + 2 # - 1)] &] (* Vincenzo Librandi, Oct 05 2012 *)

Prog

(Magma) /* The code gives only the terms up to 367: */ [n: n in [1..500] | IsPrime(10^n+2*n-1)];
(PARI) is(n)=ispseudoprime(10^n+2*n-1) \\ Charles R Greathouse IV, Jun 06 2017

Crossrefs

Cf. A173851 (accociated primes).

Sequence in context: A271624 A283090 A283143 * A127392 A236001 A258092

Adjacent sequences: A174172 A174173 A174174 * A174176 A174177 A174178

Keyword

nonn,more

Author

Vincenzo Librandi, Mar 11 2010

Extensions

a(11)-a(13) from Vincenzo Librandi, Oct 05 2012

a(14)-a(16) from Robert Price, Mar 24 2015

Status

approved