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A128396 Numbers k such that k^2 divides 16^k-1. 17
1, 3, 5, 15, 21, 39, 55, 105, 155, 165, 195, 205, 273, 465, 609, 615, 903, 915, 1155, 1265, 1365, 1705, 2067, 2145, 2255, 2265, 2373, 2667, 3045, 3081, 3255, 3795, 4305, 4515, 4895, 4965, 5115, 6045, 6123, 6355, 6405, 6765, 7077, 7455, 7917, 7995, 10065 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
MATHEMATICA
Select[Range[11000], Divisible[16^#-1, #^2]&] (* Harvey P. Dale, Dec 14 2010 *)
Join[{1}, Select[Range[11000], PowerMod[16, #, #^2]==1&]] (* Harvey P. Dale, Mar 16 2022 *)
CROSSREFS
Sequence in context: A201433 A101129 A177916 * A155173 A202505 A210111
KEYWORD
nonn,less
AUTHOR
Alexander Adamchuk, Mar 01 2007
STATUS
approved

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Last modified December 7 21:37 EST 2023. Contains 367662 sequences. (Running on oeis4.)