A055695 Numbers k such that 12^k == -1 (mod k-1).

2, 6, 30, 146, 42486, 102966, 597198, 2847366, 7998606, 13133666, 30478158, 67622310, 74476206, 101258190, 105161166, 106364286, 187605438, 230000550, 242915166, 401913582, 406756350, 444314574, 848205078, 899715894, 1508418054, 1575220350, 1578086334, 1691859102

Offset: 1

Author

Robert G. Wilson v, Jun 09 2000

Keywords

• nonn

Programs

Mathematica

Do[If[PowerMod[12, n, n-1]==n-2, Print[n]], {n, 2, 10^8}]

Extensions

Terms a(14) onward from Max Alekseyev, Oct 12 2012