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 A047523 #16 Sep 08 2022 08:44:57
%S A047523 0,1,7,8,9,15,16,17,23,24,25,31,32,33,39,40,41,47,48,49,55,56,57,63,
%T A047523 64,65,71,72,73,79,80,81,87,88,89,95,96,97,103,104,105,111,112,113,
%U A047523 119,120,121,127,128,129,135,136,137,143,144,145,151,152,153,159
%N A047523 Numbers that are congruent to {0, 1, 7} mod 8.
%H A047523 Vincenzo Librandi, <a href="/A047523/b047523.txt">Table of n, a(n) for n = 1..1000</a>
%H A047523 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,1,-1).
%F A047523 G.f.: x^2*(1+6*x+x^2) / ((1+x+x^2)*(x-1)^2). - _R. J. Mathar_, Oct 08 2011
%F A047523 From _Wesley Ivan Hurt_, Jun 13 2016: (Start)
%F A047523 a(n) = a(n-1) + a(n-3) - a(n-4) for n>4.
%F A047523 a(n) = (24*n-24+15*cos(2*n*Pi/3)+5*sqrt(3)*sin(2*Pi*n/3))/9.
%F A047523 a(3k) = 8k-1, a(3k-1) = 8k-7, a(3k-2) = 8k-8. (End)
%p A047523 A047523:=n->(24*n-24+15*cos(2*n*Pi/3)+5*sqrt(3)*sin(2*Pi*n/3))/9: seq(A047523(n), n=1..100); # _Wesley Ivan Hurt_, Jun 13 2016
%t A047523 Select[Range[0, 150], MemberQ[{0, 1, 7}, Mod[#, 8]] &] (* _Wesley Ivan Hurt_, Jun 13 2016 *)
%t A047523 LinearRecurrence[{1, 0, 1, -1}, {0, 1, 7, 8}, 100] (* _Vincenzo Librandi_, Jun 14 2016 *)
%o A047523 (Magma) [n : n in [0..150] | n mod 8 in [0, 1, 7]]; // _Wesley Ivan Hurt_, Jun 13 2016
%K A047523 nonn,easy
%O A047523 1,3
%A A047523 _N. J. A. Sloane_