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 A135914 #18 May 14 2024 03:21:31
%S A135914 1,7,27,91,291,907,2787,8491,25731,77707,234147,704491,2117571,
%T A135914 6360907,19099107,57330091,172055811,516298507,1549157667,4647997291,
%U A135914 13945040451,41837218507,125515849827,376555938091,1129684591491,3389087328907,10167329095587
%N A135914 a(n) = 4*3^n - 2*2^n - 1.
%D A135914 G. S. Lueker, Some techniques for solving recurrences, Computing Surveys, 12 (1980), 419-436.
%H A135914 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (6,-11,6).
%F A135914 From _Gary W. Adamson_, Mar 08 2008: (Start)
%F A135914 Inverse binomial transform = A134067: (1, 6, 14, 30, 62, 126, ...).
%F A135914 Second inverse binomial transform = (1, 5, 3, 5, 3, 5, 3, 5, ...). (End)
%F A135914 From _Colin Barker_, Aug 13 2012: (Start)
%F A135914 a(n) = 6*a(n-1) - 11*a(n-2) + 6*a(n-3).
%F A135914 G.f.: (1+x-4*x^2)/((1-x)*(1-2*x)*(1-3*x)). (End)
%t A135914 Table[4*3^n-2*2^n-1,{n,0,30}] (* or *) LinearRecurrence[{6,-11,6},{1,7,27},30] (* _Harvey P. Dale_, Aug 26 2019 *)
%Y A135914 Cf. A134067.
%K A135914 nonn,easy
%O A135914 0,2
%A A135914 _N. J. A. Sloane_, Mar 07 2008