%I #7 Jun 06 2021 09:03:14
%S 1,19,397841,1152331,3566699,24128658809,74683110361,216316727651,
%T 1339092172657,7967201553697
%N Numbers k such that k^3 divides 18^(k^2) + 1.
%C 19 divides a(n) for n > 1.
%Y Cf. A127263 (k^3 divides 2^(k^2) + 1).
%Y Cf. A128678, A128679, A128680, A128681, A128682, A128683, A128684, A128685.
%Y Cf. A177813, A177814, A177816, A177817, A177818, A177819, A177820.
%Y Cf. A128677 (least k > p such that (k*p)^3 divides (p-1)^(k*p)^2+1, where p = prime(n) > 2).
%K more,nonn
%O 1,2
%A _Alexander Adamchuk_, May 14 2010
%E a(6)-a(10) from _Max Alekseyev_, May 16 2010