A128399 Numbers k such that k^2 divides 19^k-1.

1, 2, 3, 4, 6, 9, 10, 12, 18, 20, 30, 36, 42, 60, 84, 90, 110, 126, 156, 180, 210, 220, 252, 294, 330, 381, 420, 468, 588, 630, 660, 724, 762, 780, 882, 930, 990, 1092, 1143, 1260, 1332, 1470, 1510, 1524, 1764, 1806, 1830, 1860, 1980, 2028, 2058, 2172, 2286, 2310

Offset: 1

Author

Alexander Adamchuk, Mar 01 2007

Keywords

• nonn

Links

• Seiichi Manyama, Table of n, a(n) for n = 1..5000

Crossrefs

Columns k=19 of A333500.

Cf. A127103, A127104, A127105, A127106, A127107, A127102, A127101, A127100, A127092, A128405, A128393, A128394, A128395, A128396, A128397, A128398, A128400, A128401, A128402, A128403, A128404.

Programs

Mathematica

Join[{1},Select[Range[3000],PowerMod[19,#,#^2]==1&]] (* Harvey P. Dale, Oct 24 2017 *)

PARI

for(k=1, 1e4, if(Mod(19, k^2)^k==1, print1(k", "))) \\ Seiichi Manyama, Mar 25 2020