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 A154266 #37 Apr 12 2025 11:34:49
%S A154266 12,39,66,93,120,147,174,201,228,255,282,309,336,363,390,417,444,471,
%T A154266 498,525,552,579,606,633,660,687,714,741,768,795,822,849,876,903,930,
%U A154266 957,984,1011,1038,1065,1092,1119,1146,1173,1200,1227,1254,1281,1308,1335
%N A154266 a(n) = 27*n + 12.
%C A154266 The identity (81*n^2 + 72*n + 17)^2 - (9*n^2 + 8*n + 2)*(27*n + 12)^2 = 1 can be written as A154295(n+1)^2 - A154262(n+1)*a(n)^2 = 1. - _Vincenzo Librandi_, Feb 03 2012
%H A154266 Vincenzo Librandi, <a href="/A154266/b154266.txt">Table of n, a(n) for n = 0..10000</a>
%H A154266 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%F A154266 From _R. J. Mathar_, Jan 05 2011: (Start)
%F A154266 G.f.: 3*(4 + 5*x)/(1-x)^2.
%F A154266 a(n) = 3*A017209(n). (End)
%F A154266 a(n) = 2*a(n-1) - a(n-2). - _Vincenzo Librandi_, Feb 02 2012
%F A154266 E.g.f.: (27*x + 12)*exp(x). - _G. C. Greubel_, Sep 08 2016
%F A154266 a(n) = A017197(3*n+1) = A008585(9*n+4). - _Elmo R. Oliveira_, Apr 12 2025
%t A154266 Range[12, 7000, 27] (* _Vladimir Joseph Stephan Orlovsky_, Jul 13 2011 *)
%t A154266 LinearRecurrence[{2, -1}, {12, 39}, 50] (* _Vincenzo Librandi_, Feb 02 2012 *)
%o A154266 (PARI) a(n)=27*n+12 \\ _Charles R Greathouse IV_, Dec 28 2011
%o A154266 (Magma) I:=[12, 39]; [n le 2 select I[n] else 2*Self(n-1)-Self(n-2): n in [1..40]]; // _Vincenzo Librandi_, Feb 02 2012
%Y A154266 Cf. A008585, A017197, A017209, A154262, A154295.
%K A154266 nonn,easy
%O A154266 0,1
%A A154266 _Vincenzo Librandi_, Jan 06 2009
%E A154266 119 replaced by 1119 - _R. J. Mathar_, Jan 07 2009