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a(n) = least k such that the remainder of 13^k divided by k is n.
49

%I #48 Nov 02 2016 11:33:09

%S 2,11,5,51,44,7,15,371285,10,74853,158,13757837,17,5805311,22,2181,38,

%T 25,30,9667,74,87,146,23441,88,19629779,35,45,70,235433,46,55,34,309,

%U 134

%N a(n) = least k such that the remainder of 13^k divided by k is n.

%C a(36) > 10^16. - _Max Alekseyev_, Oct 25 2016

%H Fausto A. C. Cariboni, <a href="/A127821/a127821_3.txt">Table of n, a(n) for n = 1..10000 with -1 for large entries where a(n) has not yet been found</a>, Oct 31 2016 [With 207 new terms, this supersedes the earlier table from Robert G. Wilson v et al.]

%H Robert G. Wilson v et al., <a href="/A127821/a127821_1.txt">Table of n, a(n) for n = 1..10000 with -1 for large entries where a(n) has not yet been found</a>, Feb 06 2007; Nov 30 2010.

%t t = Table[0, {10000} ]; k = 1; While[ k < 3500000000, a = PowerMod[13, k, k]; If[a < 10001 && t[[a]] == 0, t[[a]] = k; Print[{a, k}]]; k++ ]; t

%Y Cf. A036236, A078457, A119678, A119679, A127816, A119715, A119714, A127817, A127818, A127819, A127820.

%K nonn,hard,more

%O 1,1

%A _Alexander Adamchuk_, Jan 30 2007

%E More terms from _Robert G. Wilson v_, Feb 06 2007

%E a(264), a(798), a(884), a(896), a(976), a(980), a(152), a(171), a(296), a(464), a(824), a(870) from _Daniel Morel_, Jun 17, Nov 30 2010