

A256451


Numbers n such that 10^n + prime(n) is prime.


0




OFFSET

1,1


COMMENTS

a(11) > 10^5.  Robert Price, Mar 29 2015


LINKS

Table of n, a(n) for n=1..10.


EXAMPLE

4 is in this sequence since the fourth prime is 7 and 10^4+7=10007 is prime.


MATHEMATICA

Select[Range[100000], PrimeQ[10^# + Prime[#]] &]


PROG

(PARI) for(n=1, 10^3, if(ispseudoprime(10^n+prime(n)), print1(n, ", "))) \\ Derek Orr, Mar 29 2015
(MAGMA) [n: n in [1..770]  IsPrime(NthPrime(n) + 10^n)]; // Vincenzo Librandi, Mar 30 2015


CROSSREFS

Cf. A110065, A110066, A110067.
Sequence in context: A104465 A175759 A098515 * A059719 A264930 A226347
Adjacent sequences: A256448 A256449 A256450 * A256452 A256453 A256454


KEYWORD

nonn,hard,more


AUTHOR

Robert Price, Mar 29 2015


STATUS

approved



