A127107 Numbers n such that n^2 divides 7^n-1.

1, 2, 3, 4, 6, 8, 12, 20, 24, 40, 57, 60, 100, 114, 120, 156, 200, 220, 228, 258, 300, 312, 440, 456, 516, 600, 660, 780, 1032, 1100, 1140, 1320, 1560, 1640, 1752, 1860, 2172, 2200, 2280, 2580, 2964, 3300, 3660, 3720, 3820, 3900, 4344, 4632, 4902, 4920, 5060

Offset: 1

Author

Alexander Adamchuk, Jan 05 2007

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A127100, A127101, A127102, A127103, A123104, A127105, A127106, A127092. Cf. A067947 = numbers n such that n divides 7^n-1.

Programs

Mathematica

Select[Range[10000], IntegerQ[(PowerMod[7, #, #^2 ]-1)/#^2 ]&]