This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A177819 #9 Jun 06 2021 09:03:26 %S A177819 1,5,55,1265,11255,59455,123805,395755,635255,874115,1028555,1456015, %T A177819 2847515,3201715,3841805,4353305,6655055,6987805,13443155,16825765, %U A177819 23656765,36370015,41083405,66919765,68432705,100126015,123012395 %N A177819 Numbers k such that k^3 divides 19^(k^2) + 1. %C A177819 5 divides a(n) for n > 1. %t A177819 Select[Range[123020000],PowerMod[19,#^2,#^3]==#^3-1&] (* _Harvey P. Dale_, May 20 2021 *) %Y A177819 Cf. A127263 (k^3 divides 2^(k^2) + 1). %Y A177819 Cf. A128678, A128679, A128680, A128681, A128682, A128683, A128684, A128685. %Y A177819 Cf. A177813, A177814, A177816, A177817, A177818, A177819, A177820. %Y A177819 Cf. A128677 (least k > p such that (k*p)^3 divides (p-1)^(k*p)^2+1, where p = prime(n) > 2). %K A177819 nonn %O A177819 1,2 %A A177819 _Alexander Adamchuk_, May 14 2010 %E A177819 More terms from _Max Alekseyev_, May 16 2010