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 A364086 #59 Jul 28 2023 17:21:15 %S A364086 3,8,11,20,23,35,39,48,51,68,83,95,96,99,119,131,135,155,156,179,183, %T A364086 191,200,204,224,231,239,243,251,260,284,299,303,323,359,371,375,380, %U A364086 384,404,411,419,428,431,443,464,483,488,491,495,504,515,519,531,543,564 %N A364086 Fixed points of A002326, i.e., numbers k such that A002326(k) = k. %C A364086 It seems that a(n) = (A115591(n)-1)/2. Indeed, it follows from the definition of A115591 that if a prime p is listed in A115591, then (p-1)/2 is also listed in this sequence. %C A364086 The related case of A002326(k) = 2k is true if (and conjecturally only if) 2k+1 is a prime with primitive root 2, see A001122. %H A364086 Daniel Haase, <a href="/A364086/b364086.txt">Table of n, a(n) for n = 1..10000</a> %e A364086 The first three terms of this sequence are 3, 8, and 11. Thus, the first three fixed points of A002326 are A002326(3) = 3, A002326(8) = 8, and A002326(11) = 11. %t A364086 Select[Range[600], MultiplicativeOrder[2, 2*# + 1] == # &] (* _Amiram Eldar_, Jul 28 2023 *) %o A364086 (PARI) isok(k) = znorder(Mod(2, 2*k+1)) == k; \\ _Michel Marcus_, Jul 28 2023 %Y A364086 Cf. A002326, A115591, A001122. %K A364086 nonn,easy %O A364086 1,1 %A A364086 _Daniel Haase_, Jul 09 2023