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 A023173 #27 Apr 11 2022 12:15:13
%S A023173 1,2,11,19,22,29,31,38,41,58,59,61,62,71,79,82,89,101,109,118,122,131,
%T A023173 139,142,149,151,158,178,179,181,191,199,202,211,218,229,239,241,251,
%U A023173 262,269,271,278,281,298,302,311,323,331,349,358,359,362,379,382,389,398,401
%N A023173 Numbers k such that Fibonacci(k) == 1 (mod k).
%C A023173 Sequence contains 1, A064739(k) for all k>=0, 2*A064739(k) for k>1. - _Benoit Cloitre_, Apr 06 2002
%H A023173 Charles R Greathouse IV, <a href="/A023173/b023173.txt">Table of n, a(n) for n = 1..10000</a>
%t A023173 lst={};Do[If[Mod[Fibonacci[n],n]==1,AppendTo[lst,n]],{n,1,7!}];Take[Union[lst],5! ] (* _Vladimir Joseph Stephan Orlovsky_, Apr 03 2009 *)
%t A023173 Select[Range[500],Mod[Fibonacci[#]-1,#]==0&] (* _Harvey P. Dale_, Sep 22 2021 *)
%o A023173 (PARI) fibmod(n,m)=((Mod([1,1;1,0],m))^n)[1,2]
%o A023173 is(n)=fibmod(n,n)==1 \\ _Charles R Greathouse IV_, Oct 06 2016
%Y A023173 Cf. A000045, A045468, A003631, A064739.
%K A023173 nonn,easy
%O A023173 1,2
%A A023173 _David W. Wilson_