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 A167798 #12 Jan 04 2025 00:37:11 %S A167798 5,7,13,23,25,29,37,47,49,53,61,71,79,101,103,125,149,167,169,173,181, %T A167798 191,197,199,239,263,269,271,293,311,317,343,349,359,367,373,383,389, %U A167798 421,461,463,479,487,503,509,529,541,557,599,607,613,625,647,653,661 %N A167798 Numbers with primitive root -2. %C A167798 Numbers k such that the largest primitive root of k is k-2. - _Davide Rotondo_, Dec 20 2024 %H A167798 Vincenzo Librandi, <a href="/A167798/b167798.txt">Table of n, a(n) for n = 1..1000</a> %t A167798 pr=-2; Select[Range[2,2000], MultiplicativeOrder[pr,# ] == EulerPhi[ # ] &] %o A167798 (PARI) is(n)=if(n%2==0, return(0)); my(p=eulerphi(n)); znorder(Mod(-2, n), p)==p \\ _Charles R Greathouse IV_, Jan 04 2025 %Y A167798 Cf. A105874 (primes with primitive root -2). %K A167798 nonn %O A167798 1,1 %A A167798 _T. D. Noe_, Nov 12 2009