A177905 Numbers k such that k^3 divides 5^(k^2) - 1.

1, 2, 4, 6, 12, 26, 42, 52, 68, 78, 84, 114, 156, 186, 204, 222, 228, 372, 444, 546, 798, 876, 884, 1092, 1218, 1252, 1302, 1378, 1428, 1482, 1554, 1596, 1806, 2418, 2436, 2604, 2652, 2756, 2886, 2964, 3108, 3534, 3606, 3612, 3756, 3876, 4134, 4218, 4836

Offset: 1

Author

Alexander Adamchuk, May 14 2010

Keywords

• nonn

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..900

Crossrefs

Cf. A067946 (k divides 5^k-1), A127105 (k^2 divides 5^k-1).

Cf. A129211, A129212, A177905, A127106, A177907, A127102, A177909, A177243.

Cf. A177911, A177912, A177913, A177914, A177915, A177916, A177917, A177918, A177919, A177920.

Programs

Maple

A177905:=n->`if`(5^(n^2)-1 mod n^3 = 0, n, NULL): seq(A177905(n), n=1..10^3); # Wesley Ivan Hurt, Feb 16 2017

Mathematica

Join[{1},Select[Range[5000],PowerMod[5,#^2,#^3]==1&]] (* Harvey P. Dale, May 04 2017 *)