A177820 Numbers k such that k^3 divides 20^(k^2) + 1.

1, 3, 7, 21, 381, 903, 921, 2667, 5789, 6447, 17367, 18543, 73703, 114681, 116967, 208443, 221109, 277221, 746781, 797349, 818769, 855141, 871347, 1459101, 2205609, 2354961, 5090367, 5331669, 5692701, 6099429, 7611387, 8710041

Offset: 1

Author

Alexander Adamchuk, May 14 2010

Keywords

• nonn

Crossrefs

Cf. A127263 (k^3 divides 2^(k^2) + 1).

Cf. A128678, A128679, A128680, A128681, A128682, A128683, A128684, A128685.

Cf. A177813, A177814, A177816, A177817, A177818, A177819, A177820.

Cf. A128677 (least k > p such that (k*p)^3 divides (p-1)^(k*p)^2+1, where p = prime(n) > 2).