|
| |
|
|
A247132
|
|
Numbers k such that 2k - 1 divides 2^k + 1.
|
|
1
|
|
|
|
1, 194997, 1463649, 1957025, 4657005, 6464145, 17214725, 70930629, 76938345, 319359365, 336837501, 429872625, 486213525, 1343289717, 1831683645, 2163016845, 2430979425, 2950546137, 3463374005, 5031564525, 5608791441, 8993704797, 9596401485, 12556945401, 13492461125, 14559291285, 18429009725
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,2
|
|
|
LINKS
|
|
|
|
EXAMPLE
|
1 is in this sequence because (2^1 + 1)/(2*1 - 1) = 3.
|
|
|
MATHEMATICA
|
Select[Range[200000], IntegerQ[(2^# + 1) / (2 # - 1)] &] (* Vincenzo Librandi, Nov 20 2014 *)
|
|
|
PROG
|
(Magma) [n: n in [1..2000000] | Denominator((2^n + 1)/(2*n - 1)) eq 1];
|
|
|
CROSSREFS
|
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
|
|
|
EXTENSIONS
|
|
|
|
STATUS
|
approved
|
| |
|
|
