A179460 - OEIS

%I #8 Jul 19 2015 02:08:59

%S 2,3,5,6,7,9,10,13,14,15,17,19,21,22,27,29,30,31,33,34,35,39,41,42,49,

%T 50,51,54,55,57,61,63,65,66,69,70,71,73,75,79,82,85,86,87,89,90,91,93,

%U 97,99,101,102,103,104,105,106,107,114,115,121,122,125,126,129,133,135

%N Numbers m for which 2*A179382(m)=A002326(m-1).

%C m is in the sequence iff the set {1,2,...,2^(2*m-2)} considered in reduced residue system modulo 2*m-1 contains the same number of odd and even integers.

%e 5 in the sequence since modulo 2*5-1=9 we have {1,2,4,8,16,32}={1,2,4,8,7,5} and the last set contains 3 odd and 3 even elements.

%t fQ[n_] := Block[{r = Union@ PowerMod[2, Range[0, 2 n - 2], 2 n - 1]}, Length@ r == 2 Count[ OddQ@ r, True]]; Select[ Range@ 138, fQ] (* _Robert G. Wilson v_, Aug 26 2010 *)

%Y Cf. A002326, A179382.

%K nonn

%O 1,1

%A _Vladimir Shevelev_, Jul 14 2010

%E More terms from _Robert G. Wilson v_, Aug 26 2010