This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A273868 Numbers n such that 10^n-9^(n+1) is prime. 0
 25, 51, 91, 107, 145, 651, 1473, 2145, 5577, 12457 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(11) > 10^5. LINKS EXAMPLE 25 is a member since 10^25 - 9^26 = 3538918110773326701067759 which is a prime number. MATHEMATICA Select[Range[21, 100000], PrimeQ[10^# - 9^(# + 1)] &] PROG (PARI) is(n)=ispseudoprime(10^n-9^(n+1)) \\ Charles R Greathouse IV, Jun 08 2016 CROSSREFS Cf. A093713, A082103, A093717, A093793, A096185, A093794, A093795, A096186, A271883. Sequence in context: A042238 A042234 A042232 * A270693 A042240 A042242 Adjacent sequences:  A273865 A273866 A273867 * A273869 A273870 A273871 KEYWORD nonn,more AUTHOR Robert Price, Jun 01 2016 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 18 01:01 EDT 2018. Contains 316297 sequences. (Running on oeis4.)