A256451 Numbers n such that 10^n + prime(n) is prime.

2, 4, 27, 63, 756, 899, 8088, 15216, 47969, 50943

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