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 A155449 #33 Mar 05 2024 11:26:07
%S A155449 6,11,23,28,40,45,57,62,74,79,91,96,108,113,125,130,142,147,159,164,
%T A155449 176,181,193,198,210,215,227,232,244,249,261,266,278,283,295,300,312,
%U A155449 317,329,334,346,351,363,368,380,385,397,402,414,419,431,436,448,453
%N A155449 Numbers k == 6 or 11 (mod 17).
%C A155449 Or, numbers k such that k^2 == 2 (mod 17).
%H A155449 Vincenzo Librandi, <a href="/A155449/b155449.txt">Table of n, a(n) for n = 1..1000</a>
%H A155449 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (1,1,-1).
%F A155449 a(n) = a(n-1) + a(n-2) - a(n-3); a(1)=6, a(2)=11, a(3)=23.
%F A155449 G.f.: x*(6 + 5*x + 6*x^2)/((1 + x)*(1 - x)^2). - _Vincenzo Librandi_, May 03 2014
%F A155449 Sum_{n>=1} (-1)^(n+1)/a(n) = tan(5*Pi/34)*Pi/17. - _Amiram Eldar_, Feb 27 2023
%t A155449 LinearRecurrence[{1,1,-1},{6,11,23},100] (* _Vincenzo Librandi_, Feb 29 2012 *)
%t A155449 CoefficientList[Series[(6 + 5 x + 6 x^2)/((1 + x) (1 - x)^2), {x, 0, 60}], x] (* _Vincenzo Librandi_, May 03 2014 *)
%K A155449 nonn,easy
%O A155449 1,1
%A A155449 _Vincenzo Librandi_, Jan 22 2009
%E A155449 Simpler definition from _Franklin T. Adams-Watters_, Jun 16 2010