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 A070683 Smallest m in range 1..phi(2n+1) such that 12^m == 1 mod 2n+1, or 0 if no such number exists. 11
 0, 0, 4, 6, 0, 1, 2, 0, 16, 6, 0, 11, 20, 0, 4, 30, 0, 12, 9, 0, 40, 42, 0, 23, 42, 0, 52, 4, 0, 29, 15, 0, 4, 66, 0, 35, 36, 0, 6, 26, 0, 41, 16, 0, 8, 6, 0, 12, 16, 0, 100, 102, 0, 53, 54, 0, 112, 44, 0, 48, 11, 0, 100, 126, 0, 65, 6, 0, 136, 138, 0, 2, 4, 0, 148 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS a(n)=2*n if 2*n+1 is in A019340, otherwise a(n)<2*n. - Robert Israel, Apr 17 2019 LINKS Robert Israel, Table of n, a(n) for n = 0..10000 MAPLE f:= proc(n)   if n mod 3 = 1 then 0 else numtheory:-order(12, 2*n+1) fi end proc: 0, seq(f(n), n=1..100); # Robert Israel, Apr 16 2019 MATHEMATICA a[n_] := Module[{s}, s = SelectFirst[Range[EulerPhi[2n+1]], PowerMod[12, #, 2n+1] == 1&]; If[s === Missing["NotFound"], 0, s]]; a /@ Range[0, 100] (* Jean-François Alcover, Jun 04 2020 *) CROSSREFS Cf. A070667-A070675, A002326, A019340, A070676, A053447, A070677, A070678, A053451, A070679, A070682, A070680, A070681. Sequence in context: A276449 A056945 A324472 * A195785 A184187 A106145 Adjacent sequences:  A070680 A070681 A070682 * A070684 A070685 A070686 KEYWORD nonn,look AUTHOR N. J. A. Sloane and Amarnath Murthy, May 08 2002 STATUS approved

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Last modified December 5 00:42 EST 2020. Contains 338943 sequences. (Running on oeis4.)