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 A101197 #14 Jul 03 2023 07:52:11
%S A101197 1,3,9,25,71,199,561,1577,4439,12487,35137,98857,278151,782599,
%T A101197 2201937,6195369,17431351,49044935,137993185,388258473,1092406631,
%U A101197 3073602311,8647907569,24331808809,68460135703,192619882695
%N A101197 Lengths of successive words (starting with a) under the substitution: {a -> aab, b -> aac, c -> b}.
%H A101197 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (2, 3, -2).
%F A101197 a(n) = 2*a(n-1) + 3*a(n-2) - 2*a(n-3).
%F A101197 G.f.: -(x+1) / (-2*x^3+3*x^2+2*x-1).
%e A101197 a => aab => aabaabaac => aabaabaacaabaabaacaabaabb, thus a(0) = 1, a(1) = 3, a(2) = 9, a(3) = 25.
%p A101197 a:= n-> (<<0|1|0>, <0|0|1>, <-2|3|2>>^n. <<0, 1, 3>>)[2, 1]:
%p A101197 seq (a(n), n=0..30); # _Alois P. Heinz_, May 06 2011
%t A101197 LinearRecurrence[{2,3,-2},{1,3,9},30] (* _Harvey P. Dale_, Jan 01 2019 *)
%Y A101197 Cf. A101399, A101400.
%Y A101197 Pairwise sums of A046672.
%K A101197 easy,nonn
%O A101197 0,2
%A A101197 _Jeroen F.J. Laros_, Jan 22 2005
%E A101197 Terms >=1577 by _Alois P. Heinz_, May 06 2011