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 A047619 #16 Apr 25 2024 09:30:41
%S A047619 1,2,5,9,10,13,17,18,21,25,26,29,33,34,37,41,42,45,49,50,53,57,58,61,
%T A047619 65,66,69,73,74,77,81,82,85,89,90,93,97,98,101,105,106,109,113,114,
%U A047619 117,121,122,125,129,130,133,137,138,141,145,146,149,153,154,157
%N A047619 Numbers that are congruent to {1, 2, 5} mod 8.
%H A047619 Vincenzo Librandi, <a href="/A047619/b047619.txt">Table of n, a(n) for n = 1..3000</a>
%H A047619 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,1,-1).
%F A047619 From _Wesley Ivan Hurt_, Jun 09 2016: (Start)
%F A047619 G.f.: x*(1+x+3*x^2+3*x^3)/((x-1)^2*(1+x+x^2)).
%F A047619 a(n) = a(n-1) + a(n-3) - a(n-4) for n>4.
%F A047619 a(n) = (24*n-24-3*cos(2*n*Pi/3)+5*sqrt(3)*sin(2*n*Pi/3))/9.
%F A047619 a(3k) = 8k-3, a(3k-1) = 8k-6, a(3k-2) = 8k-7. (End)
%p A047619 A047619:=n->(24*n-24-3*cos(2*n*Pi/3)+5*sqrt(3)*sin(2*n*Pi/3))/9: seq(A047619(n), n=1..100); # _Wesley Ivan Hurt_, Jun 09 2016
%t A047619 Select[Range[0, 150], MemberQ[{1, 2, 5}, Mod[#, 8]] &] (* _Wesley Ivan Hurt_, Jun 09 2016 *)
%t A047619 Table[8 n + {1, 2, 5}, {n, 0, 100}]//Flatten (* _Vincenzo Librandi_, Jun 11 2016 *)
%t A047619 LinearRecurrence[{1,0,1,-1},{1,2,5,9},70] (* _Harvey P. Dale_, Aug 30 2021 *)
%o A047619 (Magma) [n : n in [0..150] | n mod 8 in [1, 2, 5]]; // _Wesley Ivan Hurt_, Jun 09 2016
%K A047619 nonn,easy
%O A047619 1,2
%A A047619 _N. J. A. Sloane_