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A177820
Numbers k such that k^3 divides 20^(k^2) + 1.
9
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
1,2
CROSSREFS
Cf. A127263 (k^3 divides 2^(k^2) + 1).
Cf. A128677 (least k > p such that (k*p)^3 divides (p-1)^(k*p)^2+1, where p = prime(n) > 2).
Sequence in context: A259202 A169981 A191294 * A174230 A158236 A174942
KEYWORD
nonn
AUTHOR
Alexander Adamchuk, May 14 2010
STATUS
approved