A122182 Least positive number k such that 2^k mod k = 2n, or 0 if no such k exists.

1, 3, 6, 10669, 9, 18, 3763, 1010, 20, 35, 2951, 42, 50, 27, 36, 49, 56, 110, 697, 578, 156, 540923, 70, 287, 104, 147, 4044, 970, 220, 59378, 119, 345, 66, 3007, 75, 1990362, 184, 190, 100, 115, 81, 162, 470, 406, 812, 6631, 105, 310, 160, 207, 322

Offset: 0

Author

N. J. A. Sloane, May 11 2007, Jul 18 2008

Keywords

• nonn

Crossrefs

A bisection of A036236: a(n) = A036236(2n).

Cf. A124977.

Programs

Mathematica

lpn[n_]:=Module[{k=1},While[PowerMod[2,k,k]!=2n,k++];k]; Array[lpn,60,0] (* Harvey P. Dale, Jul 23 2012 *)

Extensions

New definition from Benoit Jubin, Jul 17 2008

More terms from Max Alekseyev, May 08 2009