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 A335699 #23 Aug 05 2020 14:15:54 %S A335699 1,0,1,2,1,0,0,2,1,1,2,2,1,0,0,2,1,2,1,2,1,1,2,1,2,1,2,2,1,0,0,2,1,0, %T A335699 0,2,1,2,1,0,0,0,0,1,2,1,2,0,0,2,1,2,1,1,2,1,2,1,2,2,1,0,0,2,1,1,2,2, %U A335699 1,0,0,2,1,2,1,0,0,2 %N A335699 Irregular tree read by rows: take the Stern-Brocot tree A007305(n)/A007306(n) and set a(n) = A007306(n) - A007305(n) mod 3. %H A335699 Kiana Mittelstaedt, <a href="https://arxiv.org/abs/1902.03195">A Stochastic Approach to Eulerian Numbers</a>, arXiv:1902.03195 [math.CO], 2019. Also Amer. Math. Mnthly, 127:7 (2020), 618-628. See Fig. 5. Note that this author has omitted the two initial terms. %e A335699 The initial rows of the tree are 1,0 // 1 // 2,1 // 0,0,2,1 // 1,2,2,1,0,0,2,1 // ... %Y A335699 Cf. A002487, A007305, A007306, A049448, A049449, A057431. %K A335699 nonn,tabf %O A335699 0,4 %A A335699 _N. J. A. Sloane_, Aug 05 2020