A055686 Numbers k such that 3^k == -1 (mod k-1).

2, 3, 5, 6, 15, 245, 366, 435, 855, 2295, 3795, 5967, 7875, 10878, 26475, 33915, 117615, 188775, 231435, 284355, 487635, 501039, 589155, 593775, 621675, 755595, 1255815, 1306935, 1642095, 1911195, 2193125, 2434755, 2484675, 2507835

Offset: 1

Author

Robert G. Wilson v, Jun 09 2000

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A055685, A055687, A055688, A055689, A055690, A055691, A055692, A055693, A055694, A055695.

Programs

Mathematica

Do[If[PowerMod[3, n, n-1]==n-2, Print[n]], {n, 2, 10^7}]