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 A097803 #33 Feb 18 2025 15:36:53
%S A097803 3,9,27,57,99,153,219,297,387,489,603,729,867,1017,1179,1353,1539,
%T A097803 1737,1947,2169,2403,2649,2907,3177,3459,3753,4059,4377,4707,5049,
%U A097803 5403,5769,6147,6537,6939,7353,7779,8217,8667,9129,9603,10089,10587,11097,11619,12153,12699
%N A097803 a(n) = 3*(2*n^2 + 1).
%C A097803 a(n) is also the number of Arnoux-Rauzy factors of length (n+1) over a 3-letter alphabet. - Genevieve Paquin (genevieve.paquin(AT)univ-savoie.fr), Nov 07 2008
%H A097803 Harvey P. Dale, <a href="/A097803/b097803.txt">Table of n, a(n) for n = 0..1000</a>
%H A097803 F. Mignosi and L. Q. Zamboni, <a href="http://dx.doi.org/10.4064/aa101-2-4">On the number of Arnoux-Rauzy words</a>, Acta arith., 101 (2002), no. 2, 121-129. [From Genevieve Paquin (genevieve.paquin(AT)univ-savoie.fr), Nov 07 2008]
%H A097803 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F A097803 From _Harvey P. Dale_, Dec 29 2011: (Start)
%F A097803 a(0)=3, a(1)=9, a(2)=27, a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3).
%F A097803 G.f.: -3*(3*x^2+1)/(x-1)^3. (End)
%F A097803 From _Elmo R. Oliveira_, Feb 18 2025: (Start)
%F A097803 E.g.f.: 3*exp(x)*(1 + 2*x + 2*x^2).
%F A097803 a(n) = 3*A058331(n). (End)
%t A097803 Table[ 3(2*n^2 + 1), {n, 0, 44}] (* _Robert G. Wilson v_, Aug 26 2004 *)
%t A097803 3(2Range[0,50]^2+1) (* or *) LinearRecurrence[{3,-3,1},{3,9,27},50] (* _Harvey P. Dale_, Dec 29 2011 *)
%o A097803 (PARI) a(n)=3*(2*n^2+1) \\ _Charles R Greathouse IV_, Jun 17 2017
%Y A097803 Cf. A058331, A097802.
%K A097803 nonn,easy
%O A097803 0,1
%A A097803 _George E. Antoniou_, Aug 25 2004
%E A097803 More terms from _Robert G. Wilson v_ and Mark Hudson (mrmarkhudson(AT)hotmail.com), Aug 26 2004