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A085879
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Smallest n-th power k^n == 1 (mod 10), where k>1.
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0
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11, 81, 1331, 81, 161051, 531441, 19487171, 6561, 2357947691, 3486784401, 285311670611, 531441, 34522712143931, 22876792454961, 4177248169415651, 43046721, 505447028499293771, 150094635296999121, 61159090448414546291, 3486784401, 7400249944258160101211, 984770902183611232881, 895430243255237372246531
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OFFSET
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1,1
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LINKS
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FORMULA
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For n==0 (mod 4), a(n) = 3^n; for n==1,3 (mod 4), a(n) = 11^n; for n==2 (mod 4), a(n)=9^n. - Max Alekseyev, Dec 06 2013
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MATHEMATICA
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snp[n_]:=Module[{k=2}, While[PowerMod[k, n, 10]!=1, k++]; k^n]; Array[snp, 30] (* Harvey P. Dale, Aug 07 2023 *)
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PROG
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(PARI) a(n) = [3, 11, 9, 11][n%4+1]^n
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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