A224506 Numbers k such that 9^k - k is prime.

2, 70, 88, 6562, 9100, 11758, 34334, 39212, 120590

Offset: 1

Author

Alex Ratushnyak, Apr 08 2013

Keywords

• nonn
• more

Comments

a(7) > 20000. - Giovanni Resta, Apr 09 2013

a(10) > 2*10^5. - Robert Price, Mar 12 2014

Crossrefs

Cf. A048744, A058037, A057908, A058046, A058829, A224470, A224471.

Programs

Mathematica

Select[Range[1000], PrimeQ[9^# - #] &] (* Alonso del Arte, Apr 11 2013 *)

PARI

is(n)=ispseudoprime(9^n-n) \\ Charles R Greathouse IV, Jun 13 2017

Extensions

a(6) from Giovanni Resta, Apr 09 2013

a(7)-a(9) from Robert Price, Mar 12 2014