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 A154571 #21 Sep 08 2022 08:45:40
%S A154571 0,3,4,5,7,8,12,15,16,17,19,20,24,27,28,29,31,32,36,39,40,41,43,44,48,
%T A154571 51,52,53,55,56,60,63,64,65,67,68,72,75,76,77,79,80,84,87,88,89,91,92,
%U A154571 96,99,100,101,103,104,108,111,112,113,115,116,120,123,124
%N A154571 Numbers that are congruent to {0, 3, 4, 5, 7, 8} mod 12.
%H A154571 G. C. Greubel, <a href="/A154571/b154571.txt">Table of n, a(n) for n = 1..1000</a>
%H A154571 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,1,-1).
%F A154571 From _Chai Wah Wu_, May 29 2016: (Start)
%F A154571 a(n) = a(n-1) + a(n-6) - a(n-7) for n>7.
%F A154571 G.f.: x^2*(4*x^5 + x^4 + 2*x^3 + x^2 + x + 3)/(x^7 - x^6 - x + 1). (End)
%F A154571 From _Wesley Ivan Hurt_, Jun 16 2016: (Start)
%F A154571 a(n) = (12*n - 15 - cos(n*Pi) - 5*cos(n*Pi/3) - sqrt(3)*(2*cos((1-4*n)*Pi/6) - 3*sin(n*Pi/3)))/6.
%F A154571 a(6k) = 12k-4, a(6k-1) = 12k-5, a(6k-2) = 12k-7, a(6k-3) = 12k-8, a(6k-4) = 12k-9, a(6k-5) = 12k-12. (End)
%F A154571 Sum_{n>=2} (-1)^n/a(n) = (15-8*sqrt(3))*Pi/72 + log(2)/4. - _Amiram Eldar_, Dec 31 2021
%p A154571 A154571:=n->(12*n-15-cos(n*Pi)-5*cos(n*Pi/3)-sqrt(3)*(2*cos((1-4*n)*Pi/6)-3*sin(n*Pi/3)))/6: seq(A154571(n), n=1..100); # _Wesley Ivan Hurt_, Jun 16 2016
%t A154571 LinearRecurrence[{1, 0, 0, 0, 0, 1, -1}, {0, 3, 4, 5, 7, 8, 12}, 50] (* _G. C. Greubel_, May 29 2016 *)
%o A154571 (Magma) [n : n in [0..150] | n mod 12 in [0, 3, 4, 5, 7, 8]]; // _Wesley Ivan Hurt_, May 29 2016
%Y A154571 Cf. A113829.
%K A154571 easy,nonn
%O A154571 1,2
%A A154571 _Omar E. Pol_, Jan 12 2009