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A055692
Numbers k such that 9^k == -1 (mod k-1).
3
2, 3, 11, 42, 147, 13818, 21450, 27594, 41370, 55011, 126291, 265722, 417123, 1315635, 3994571, 5704611, 6860490, 9298842, 13941354, 14349027, 17658578, 20382810, 26557874, 27841338, 69831363, 86550090, 113272170, 130457571, 163013235, 192688650, 211142538, 333792522
OFFSET
1,1
MATHEMATICA
Do[If[PowerMod[9, n, n-1]==n-2, Print[n]], {n, 2, 10^8}]
PROG
(PARI) isok(k) = Mod(9, k-1)^k == -1; \\ Michel Marcus, Jul 12 2021
CROSSREFS
Cf. A001019.
Sequence in context: A081173 A179266 A265779 * A051075 A051087 A051081
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jun 09 2000
STATUS
approved