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 A296217 #4 Dec 09 2017 19:28:38 %S A296217 1,2,6,26,112,484,2088,9008,38862,167658,723308,3120486,13462360, %T A296217 58079138,250564260,1080981064,4663554414,20119445656,86799050160, %U A296217 374467330636,1615522076050,6969664279584,30068434774274,129720849313094,559639996988064,2414391579204576 %N A296217 Solution of the complementary equation a(n) = a(1)*b(n-2) + a(2)*b(n-3) + ... + a(n-1)*b(0), where a(0) = 1, a(1) = 2, b(0) = 3, and (a(n)) and (b(n)) are increasing complementary sequences. %C A296217 The increasing complementary sequences a() and b() are uniquely determined by the titular equation and initial values. See A295862 for a guide to related sequences. %H A296217 Clark Kimberling, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL10/Kimberling/kimberling26.html">Complementary equations</a>, J. Int. Seq. 19 (2007), 1-13. %e A296217 a(0) =1, a(1) = 2, b(0) = 3, b(1) = 4, b(2) = 4 %e A296217 a(2) = a(1)*b(0) = 2 %e A296217 Complement: (b(n)) = (3, 4, 5, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, ...) %t A296217 a[0] = 1; a[1] = 2; b[0] = 3; %t A296217 a[n_] := a[n] = Sum[a[k]*b[n - k - 1], {k, 1, n - 1}]; %t A296217 b[n_] := b[n] = mex[Flatten[Table[Join[{a[n]}, {a[i], b[i]}], {i, 0, n - 1}]]]; %t A296217 u = Table[a[n], {n, 0, 200}]; (* A296217 *) %t A296217 Table[b[n], {n, 0, 20}] %t A296217 N[Table[a[n]/a[n - 1], {n, 1, 200, 10}], 200]; %t A296217 RealDigits[Last[t], 10][[1]] (* A296218 *) %Y A296217 Cf. A296000, A296218. %K A296217 nonn,easy %O A296217 0,2 %A A296217 _Clark Kimberling_, Dec 08 2017