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 A385228 #23 Jul 07 2025 10:44:06 %S A385228 1,5,9,7,29,33,41,53,65,69,81,89,105,113,25,35,47,51,15,173,189,209, %T A385228 221,233,245,83,261,273,281,57,293,77,309,107,329,11,115,123,393,135, %U A385228 413,429,441,453,473,97,509,129,131,175,545,137,561,83,585,593,149,629,641,645,653,713,725 %N A385228 Odd multiplicative orders of -2 modulo primes. %C A385228 a(n) is the multiplicative order of -2 modulo A163183(n). %C A385228 Odd elements in A337878 (with first term changed to 1). %H A385228 Jianing Song, <a href="/A385228/b385228.txt">Table of n, a(n) for n = 1..10000</a> %t A385228 Select[Map[MultiplicativeOrder[-2, #] &, Prime[Range[250]]], OddQ] (* _Paolo Xausa_, Jun 28 2025 *) %o A385228 (PARI) forprime(p=3, 1e4, z=znorder(Mod(-2, p)); if(z%2, print1(z, ", "))) %Y A385228 Cf. A337878, A163183 (corresponding primes). %Y A385228 Cf. other bases: A139686 (base 2), A385226 (base 3), A385227 (base 4), A385193 (base 5), this sequence (base -2), A385229 (base -3), A385230 (base -4), A385231 (base -5). %K A385228 nonn,easy %O A385228 1,2 %A A385228 _Jianing Song_, Jun 22 2025