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 A274193 #5 Jun 16 2016 14:00:55 %S A274193 1,1,1,1,1,1,1,1,1,1,1,2,1,1,1,1,2,2,1,1,1,1,2,2,2,1,1,1,1,3,3,2,2,1, %T A274193 1,1,1,3,4,3,2,2,1,1,1,1,4,4,4,3,2,2,1,1,1,1,5,6,5,4,3,2,2,1,1,1,1,6, %U A274193 7,7,5,4,3,2,2,1,1,1,1,8,9,8,7,5,4,3 %N A274193 Triangular array read by rows: g(n,k) = 1 for n >= 0; g(n,k) = 0 if k > n; g(n,k) = g(n-1,k-1) + g(n-1,3k) for n > 0, k > 1. %H A274193 Clark Kimberling, <a href="/A274193/b274193.txt">Table of n, a(n) for n = 0..10000</a> %e A274193 First 10 rows: %e A274193 1 %e A274193 1 1 %e A274193 1 1 1 %e A274193 1 1 1 1 %e A274193 1 2 1 1 1 %e A274193 1 2 2 1 1 1 %e A274193 1 2 2 2 1 1 1 %e A274193 1 3 3 2 2 1 1 1 %e A274193 1 3 4 3 2 2 1 1 1 %e A274193 1 4 4 4 3 2 2 1 1 1 %t A274193 g[n_, 0] = g[n, 0] = 1; %t A274193 g[n_, k_] := g[n, k] = If[k > n, 0, g[n - 1, k - 1] + g[n - 1, 3 k]]; %t A274193 t = Table[g[n, k], {n, 0, 14}, {k, 0, n}] %t A274193 TableForm[t] (* A274193 array *) %t A274193 u = Flatten[t] (* A274193 sequence *) %Y A274193 Cf. A274194 (row sums), A274195, A274200 (limiting reverse row), A274190, A274196. %K A274193 nonn,tabl,easy %O A274193 0,12 %A A274193 _Clark Kimberling_, Jun 14 2016