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 A004494 #20 Dec 27 2023 08:31:37
%S A004494 5,3,4,8,6,7,2,0,1,14,12,13,17,15,16,11,9,10,23,21,22,26,24,25,20,18,
%T A004494 19,32,30,31,35,33,34,29,27,28,41,39,40,44,42,43,38,36,37,50,48,49,53,
%U A004494 51,52,47,45,46,59,57,58,62,60,61,56,54,55,68,66,67,71,69
%N A004494 Tersum n + 5.
%H A004494 <a href="/index/Rec#order_10">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,0,0,0,1,-1).
%F A004494 Tersum m + n : write m and n in base 3 and add mod 3 with no carries, e.g. 5 + 8 = "21" + "22" = "10" = 1.
%t A004494 LinearRecurrence[{1, 0, 0, 0, 0, 0, 0, 0, 1, -1}, {5, 3, 4, 8, 6, 7,
%t A004494 2, 0, 1, 14}, 80] (* _Jinyuan Wang_, Mar 10 2020 *)
%o A004494 (Python) # T(n, m) in A004489
%o A004494 def a(n): return T(n, 5)
%o A004494 print([a(n) for n in range(68)]) # _Michael S. Branicky_, May 03 2021
%Y A004494 Cf. A004489.
%K A004494 nonn,easy
%O A004494 0,1
%A A004494 _N. J. A. Sloane_