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%I A128680 #12 Jun 08 2021 02:22:49
%S A128680 1,7,203,1379,11977,39991,577129,2359469,4780447,6521291,6640739,
%T A128680 9904979,21511301,28434413,34050611,113694413,189117439,222281549,
%U A128680 250163599,282046373,391803601,941748059,1269166759,1308225583
%N A128680 Numbers k such that k^3 divides 6^(k^2) + 1.
%C A128680 7 divides a(n) for n > 1.
%t A128680 Select[Range[5*10^6], Mod[ 6^(#^2)+1, #^3]==0 &] (* _G. C. Greubel_, Jan 18 2018 *)
%Y A128680 Cf. A127263 (numbers k such that k^3 divide 2^(k^2)+1).
%Y A128680 Cf. A128677 (least k > p such that (k*p)^3 divides (p-1)^(k*p)^2+1, where p = prime(n) > 2).
%Y A128680 Cf. A128678, A128679, A128681, A128682, A128683, A128684, A128685.
%K A128680 hard,nonn
%O A128680 1,2
%A A128680 _Alexander Adamchuk_, Mar 31 2007
%E A128680 More terms from _Ryan Propper_, Jan 13 2008

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