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%I #21 Feb 26 2019 09:31:09
%S 1,3,2,3,9,5,6,6,4,9,3,11,10,27,14,5,15,6,18,6,10,7,18,23,21,12,26,10,
%T 9,29,30,9,6,33,33,35,9,30,15,39,81,41,4,42,11,6,15,18,24,45,50,51,6,
%U 53,18,18,14,22,18,12,55,30,50,7,21,65,9,54,34,69,69
%N 2*a(n) is the multiplicative order of 2 mod 3*(2n-1).
%C 2*a(n) is the smallest m such that 3*(2n-1) | (2^m+1).
%H Muniru A Asiru, <a href="/A216829/b216829.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A216833(n)/2.
%t Table[MultiplicativeOrder[2, 3*(2*n-1)], {n, 100}]/2 (* _T. D. Noe_, Sep 19 2012 *)
%o (PARI) vector(100,n,znorder(Mod(2,3*(2*n-1)))/2) \\ _Joerg Arndt_, Sep 14 2012.
%o (GAP) List([1..70],n->OrderMod(2,3*(2*n-1))/2); # _Muniru A Asiru_, Feb 26 2019
%Y Cf. A003558, A002326, A216469, A216833.
%K nonn
%O 1,2
%A _V. Raman_, Sep 17 2012