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A128403
Numbers k such that k^2 divides 23^k-1.
16
1, 2, 4, 6, 8, 11, 12, 20, 22, 24, 40, 42, 44, 60, 66, 78, 84, 88, 120, 132, 156, 168, 212, 220, 264, 312, 420, 424, 440, 444, 462, 474, 546, 620, 636, 660, 780, 820, 840, 858, 888, 924, 948, 1014, 1060, 1092, 1218, 1220, 1240, 1272, 1320, 1560, 1640, 1716
OFFSET
1,2
LINKS
MATHEMATICA
Join[{1}, Select[Range[2000], PowerMod[23, #, #^2]==1&]] (* Harvey P. Dale, May 02 2015 *)
KEYWORD
nonn,less
AUTHOR
Alexander Adamchuk, Mar 01 2007
STATUS
approved