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A128685
Numbers k such that k^3 divides 12^(k^2) + 1.
20
1, 13, 1027, 52741, 468481, 2890927, 4166539, 37009999, 228383233, 999884119, 1345997497, 1900627417, 2126334691, 4499474941, 5037873529, 11728490839, 104180336299, 105897267463, 150149565943, 926550776281, 4056529870783
OFFSET
1,2
COMMENTS
13 divides a(n) for n > 1.
MATHEMATICA
Select[Range[5*10^6], Mod[ 12^(#^2)+1, #^3]==0 &] (* G. C. Greubel, Jan 18 2018 *)
KEYWORD
hard,nonn
AUTHOR
Alexander Adamchuk, Mar 31 2007
EXTENSIONS
16 more terms from Ryan Propper, Dec 03 2007
Terms a(17) onward from Max Alekseyev, May 14 2010
STATUS
approved