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 A378384 #20 Dec 21 2024 00:42:48
%S A378384 1,1,1,3,5,9,8,4,3,6,4,4,5,4,4,4,3,2,9,5,7,3,6,7,7,2,7,7,7,3,8,9,2,1,
%T A378384 3,6,1,1,8,1,1,1,3,5,9,8,4,3,6,4,4,5,4,4,4,3,2,9,5,7,3,6,7,7,2,7,7,7,
%U A378384 3,8,9,2,1,3,6,1,1,8,1,1,1,3,5,9,8,4,3,6
%N A378384 Digital root of the sum of the previous 3 terms; a(0) = a(1) = a(2) = 1.
%C A378384 This differs from A112661 which is sum of digits of sum of previous 3 terms.
%C A378384 Digital root of A000213 (tribonacci numbers beginning {1,1,1}).
%C A378384 This has a period of 39 beginning with the first term.
%C A378384 Decimal expansion of 12373315960504936995263080863765792902/111111111111111111111111111111111111111 = 0.[111359843644544432957367727773892136118] (periodic).
%H A378384 <a href="/index/Rec#order_39">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1).
%F A378384 a(n) = A010888(A000213(n)).
%t A378384 Nest[Append[#,ResourceFunction["AdditiveDigitalRoot"][Total[Take[#,-3]]]]&,{1,1,1},85]
%Y A378384 Cf. A000213, A010888, A112661.
%K A378384 nonn,base,easy
%O A378384 0,4
%A A378384 _James C. McMahon_, Nov 24 2024