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 A187532 #25 Mar 18 2024 19:48:25
%S A187532 1,4,16,7,9,17,11,6,5,1,4,16,7,9,17,11,6,5,1,4,16,7,9,17,11,6,5,1,4,
%T A187532 16,7,9,17,11,6,5,1,4,16,7,9,17,11,6,5,1,4,16,7,9,17,11,6,5,1,4,16,7,
%U A187532 9,17,11,6,5,1,4,16,7,9,17,11,6,5,1,4,16,7,9,17,11,6,5
%N A187532 a(n) = 4^n mod 19.
%C A187532 Period 9: repeat (1,4,16,7,9,17,11,6,5).
%C A187532 Also continued fraction expansion of (13140908+sqrt(323139488118562))/24969762. - _Bruno Berselli_, Sep 09 2011
%H A187532 Vincenzo Librandi, <a href="/A187532/b187532.txt">Table of n, a(n) for n = 0..1000</a>
%H A187532 <a href="/index/Rec#order_09">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,0,0,0,1).
%F A187532 a(n+9) = a(n).
%F A187532 G.f.: (1 + 4*x + 16*x^2 + 7*x^3 + 9*x^4 + 17*x^5 + 11*x^6 + 6*x^7 + 5*x^8)/((1-x)*(1+x+x^2)*(1+x^3+x^6)). - _Bruno Berselli_, Sep 09 2011
%t A187532 PowerMod[4, Range[0, 100], 19] (* or *)
%t A187532 PadRight[{}, 100, {1, 4, 16, 7, 9, 17, 11, 6, 5}] (* _Paolo Xausa_, Mar 17 2024 *)
%o A187532 (Magma) [4^n mod 19 : n in [0..80]]; // _Vincenzo Librandi_, Sep 09 2011
%o A187532 (PARI) a(n)=lift(Mod(4,19)^n) \\ _Charles R Greathouse IV_, Mar 22 2016
%Y A187532 Cf. A036120, A070342, A070373, A070395, A070421.
%K A187532 nonn,easy
%O A187532 0,2
%A A187532 _M. F. Hasler_, Mar 10 2011