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 A196663 #23 Mar 18 2025 13:47:41
%S A196663 1,9,117,1521,19773,257049,3341637,43441281,564736653,7341576489,
%T A196663 95440494357,1240726426641,16129443546333,209682766102329,
%U A196663 2725875959330277,35436387471293601,460673037126816813,5988749482648618569,77853743274432041397,1012098662567616538161
%N A196663 Expansion of g.f. (1-4*x)/(1-13*x).
%H A196663 <a href="/index/Rec#order_01">Index entries for linear recurrences with constant coefficients</a>, signature (13).
%F A196663 a(0) = 1, a(n) = 9*13^(n-1) for n>0.
%F A196663 a(n) = Sum_{k=0..n} A193722(n,k)*4^k.
%F A196663 From _Elmo R. Oliveira_, Mar 18 2025: (Start)
%F A196663 E.g.f.: (9*exp(13*x) + 4)/13.
%F A196663 a(n) = 13*a(n-1). (End)
%Y A196663 Cf. A002001, A193722, A196661, A196662.
%K A196663 nonn,easy
%O A196663 0,2
%A A196663 _Philippe Deléham_, Oct 05 2011