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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).
Sequence in context: A338787 A353619 A133710 * A368391 A274875 A061548
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, May 05 2007
STATUS
approved

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Last modified March 29 02:23 EDT 2024. Contains 371264 sequences. (Running on oeis4.)