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 A296218 #7 Mar 15 2025 02:57:43 %S A296218 4,3,1,4,1,8,6,9,6,3,4,0,2,6,0,0,1,2,6,3,9,6,2,5,4,6,9,6,2,5,5,3,9,9, %T A296218 3,1,3,1,7,3,1,5,4,3,3,5,3,7,7,6,9,7,3,4,5,0,0,3,0,4,5,3,5,4,9,2,4,3, %U A296218 5,8,4,1,6,4,5,9,6,9,2,4,1,0,0,4,3,4 %N A296218 Decimal expansion of the limiting ratio of terms in A296217. %e A296218 A296217(n)/A296217(n-1) -> 4.31418696340... %e A296218 See A296000 for a guide to related sequences and limiting ratios. %t A296218 a[0] = 1; a[1] = 2; b[0] = 3; %t A296218 a[n_] := a[n] = Sum[a[k]*b[n - k - 1], {k, 1, n - 1}]; %t A296218 b[n_] := b[n] = mex[Flatten[Table[Join[{a[n]}, {a[i], b[i]}], {i, 0, n - 1}]]]; %t A296218 u = Table[a[n], {n, 0, 200}]; (* A296217 *) %t A296218 Table[b[n], {n, 0, 20}] %t A296218 N[Table[a[n]/a[n - 1], {n, 1, 200, 10}], 200]; %t A296218 RealDigits[Last[t], 10][[1]] (* A296218 *) %Y A296218 Cf. A296000, A296215, A296217. %K A296218 nonn,easy,cons %O A296218 1,1 %A A296218 _Clark Kimberling_, Dec 08 2017