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 A103369 #19 Feb 16 2025 08:32:56
%S A103369 1,4,37,4,89,89,1,89,37,1,4,89,1,89,16,16,89,37,1,20,89,89,1,20,89,16,
%T A103369 89,1,89,37,1,1,37,89,89,89,37,58,37,16,89,42,89,1,89,89,37,89,1,89,
%U A103369 16,89,89,89,89,37,37,58,37,89,37,16,89,89,37,89,89,1,16,1,89,89,58
%N A103369 Number in the 2-digitaddition sequence at which the eventually periodic part starts.
%C A103369 a(A007770(n)) = 1; a(A031177(n)) > 1. - _Reinhard Zumkeller_, Mar 16 2013
%H A103369 Reinhard Zumkeller, <a href="/A103369/b103369.txt">Table of n, a(n) for n = 1..10000</a>
%H A103369 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Digitaddition.html">Digitaddition</a>
%e A103369 The 2-digitaddition sequence for n = 3 is {3, 9, 81, 65, 61, 37, 58, 89, 145, 42, 20, 4, 16, 37, ...}, so a(3) = 37.
%o A103369 (Haskell)
%o A103369 a103369 = until (`elem` a039943_list) a003132
%o A103369 a103369_list = map a103369 [1..]
%o A103369 -- _Reinhard Zumkeller_, Oct 17 2011, Aug 24 2011
%Y A103369 Cf. A007770, A031176, A003132, A039943.
%K A103369 nonn,base
%O A103369 1,2
%A A103369 _Eric W. Weisstein_, Feb 02 2005