|
|
A217383
|
|
Numbers k such that 8^k - 9 is prime.
|
|
1
|
|
|
3, 7, 11, 47, 81, 95, 107, 179, 233, 243, 947, 2817, 2859, 3233, 7563, 11307, 218615, 225587
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
All terms are equal to 1/3 of the multiples of 3 in A059610.
Naturally these numbers are odd since 8^(2n)-9 = (8^n-3)(8^n+3) is composite. - Bruno Berselli, Oct 04 2012
|
|
LINKS
|
|
|
MATHEMATICA
|
Select[Range[10000], PrimeQ[8^# - 9] &]
|
|
PROG
|
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,more
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|