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A128405
Numbers k such that k^2 divides 12^k - 1.
16
1, 11, 253, 11891, 768361, 36112967, 61488361, 154261943, 2936791979, 61057324141, 67546215517, 107342336783, 186740152357, 347036920549, 429306186947, 468493520891, 635974117823, 797688507253, 3174672129299
OFFSET
1,2
COMMENTS
11 divides all except the first term.
All terms are congruent to +-1 (mod 12). - Robert G. Wilson v, Dec 19 2014
MATHEMATICA
fQ[n_] := Mod[ PowerMod[12, n, n^2] - 1, n^2] == 0; k = 1; lst = {}; While[k < 100000001, If[ fQ@ k, AppendTo[lst, k]; Print@ k]; k += 10; If[ fQ@ k, AppendTo[lst, k]; Print@ k]; k += 2]; lst (* Robert G. Wilson v, Dec 19 2014 *)
KEYWORD
nonn,less
AUTHOR
Alexander Adamchuk, Mar 01 2007
EXTENSIONS
a(6)-a(8) from Farideh Firoozbakht, Mar 05 2007
Terms a(9) onward from Max Alekseyev, May 06 2010
STATUS
approved