A337829 Odd integers k such that 5^((k-1)/2) + 1 == 0 (mod k*(k-1)/2).

3, 7, 43, 53, 127, 163, 487, 677, 883, 2647, 8527, 8803, 14407, 18523, 26407, 32887, 35323, 39367, 71443, 105967, 184087, 184843, 230203, 265483, 319327, 388963, 425083, 543607, 554527, 651043, 688087, 690607, 698923, 796447, 887923, 924043, 1001323

Offset: 1

Author

Benoit Cloitre, Sep 24 2020

Keywords

• nonn

Comments

The first 564 terms are prime.

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..564

Crossrefs

Cf. A337818.

Programs

Mathematica

Select[Range[3, 10^6, 2], PowerMod[5, (# - 1)/2, (t = #*(# - 1)/2)] == t - 1 &] (* Amiram Eldar, Sep 24 2020 *)