|
|
A130061
|
|
Numbers k such that k divides 3^((k-1)/2) - 2^((k-1)/2) - 1.
|
|
4
|
|
|
1, 3, 35, 147, 195, 219, 291, 399, 579, 583, 723, 939, 1011, 1023, 1227, 1299, 1371, 1443, 1731, 1803, 2019, 2307, 2499, 2811, 3003, 3027, 3099, 3387, 3459, 3603, 3747, 3891, 3963, 4467, 4623, 4827, 4971, 5187, 5259, 5331, 5403, 5619, 5979, 6051, 6267
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
It appears that all terms are composite except a(1) = 1 and a(2) = 3. Most listed terms are divisible by 3, except {1, 35, 583, 70643, ...}.
|
|
LINKS
|
|
|
MATHEMATICA
|
Select[ Range[10000], Mod[ PowerMod[3, (#-1)/2, # ] - PowerMod[2, (#-1)/2, # ] -1, # ]==0&]
|
|
CROSSREFS
|
Cf. A097934 (primes p that divide 3^((p-1)/2) - 2^((p-1)/2).
Cf. A038876 (primes p such that 6 is a square mod p).
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|