A171261 Numbers n such that prime(n)^n-n is prime.

2, 8, 24, 42

Offset

1,1

Comments

All terms are even. There is no further term up to 10000. So the prime

corresponding to the next term if it exists has more than 50200 digits.

1 and 2 are the only known numbers n (up to 10000) such that prime(n)^n+n

is prime.

Links

Table of n, a(n) for n=1..4.

Example

prime(2)^2-2=3^2-2=7 is prime, so 2 is in the sequence.

Mathematica

Do[If[PrimeQ[Prime[n]^n-n], Print[n]], {n, 50000}]

Crossrefs

Cf. A000040.

Sequence in context: A062247 A284951 A357635 * A084744 A122547 A152132

Adjacent sequences: A171258 A171259 A171260 * A171262 A171263 A171264

Keyword

nonn

Author

Farideh Firoozbakht, Dec 07 2009

Status

approved