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 A380532 #31 Jul 07 2025 10:43:48
%S A380532 1,1,0,3,10,4,16,18,11,7,6,36,20,21,23,52,58,15,11,10,72,78,41,44,96,
%T A380532 50,51,53,54,112,21,130,136,138,74,150,156,27,83,172,178,30,38,192,
%U A380532 196,66,70,111,113,57,232,238,40,50,256,131,134,54,276,140
%N A380532 a(n) is the multiplicative order of -5 modulo prime(n); a(3) = 0 for completion.
%H A380532 Jianing Song, <a href="/A380532/b380532.txt">Table of n, a(n) for n = 1..10000</a>
%t A380532 A380532[n_] := If[n == 3, 0, MultiplicativeOrder[-5, Prime[n]]];
%t A380532 Array[A380532, 100] (* _Paolo Xausa_, Jun 29 2025 *)
%o A380532 (PARI) a(n,{k=-5}) = my(p = prime(n)); if(k%p==0, 0, znorder(Mod(k,p)))
%Y A380532 Cf. A105877 (primes having primitive root -5).
%Y A380532 Cf. bases 2..10: A014664, A062117, A082654, A211241, A211242, A211243, A211244, A211245, A002371.
%Y A380532 Cf. bases -2..-10: A337878 (if first term 1), A380482, A380531, this sequence, A380533, A380540, A380541, A380542, A385222.
%K A380532 nonn,easy
%O A380532 1,4
%A A380532 _Jianing Song_, Jun 27 2025