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1, 2, 6, 8, 18, 24, 31, 38, 72, 105, 129, 630, 1285, 1542, 2048, 3112, 3512, 7710, 7760, 9728, 27594, 48834, 60787, 104694, 140896, 282224, 384800, 683720, 1205998, 1240672, 1407592, 4012472, 4429250, 4628480, 16657248, 69273666, 107700228, 254290896, 319233186
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OFFSET
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1,2
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LINKS
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FORMULA
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EXAMPLE
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First few terms of A001917 are 1, 1, 2, 1, 1, 2, 1, 2, 1, 6, so a(1) to a(3) are 1, 2, 6.
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MATHEMATICA
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ord[n_]:=Module[{x=1}, While[PowerMod[2, x, n]!=1, x++]; (n-1)/x]; DeleteDuplicates[ ord/@Prime[Range[2, 10^5]], GreaterEqual] (* The program generates the first 21 terms of the sequence. *) (* Harvey P. Dale, Oct 09 2022 *)
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PROG
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(Magma) R:=[]; r:=0; for n in [2..100000] do p:=NthPrime(n); a:=(p-1)/Modorder(2, p); if r lt a then r:=a; Append(~R, a); end if; end for; print R;
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CROSSREFS
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Cf. A001917 ((p-1)/x, where p = prime(n) and x = smallest positive integer such that 2^x == 1 mod p), A152597 (where records occur in A001917).
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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