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 A036551 #16 Aug 24 2016 09:24:02 %S A036551 1,3,17,105,641,3873,23297,139905,839681,5038593,30232577,181397505, %T A036551 1088389121,6530342913,39182073857,235092475905,1410554920961, %U A036551 8463329656833,50779978203137,304679869743105,1828079219507201,10968475319140353,65810851919036417 %N A036551 a(n) = 2^(n-1)*(3^n-1) + 1. %H A036551 Colin Barker, <a href="/A036551/b036551.txt">Table of n, a(n) for n = 0..1000</a> %H A036551 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (9,-20,12). %F A036551 a(n) = T(n, n), array T given by A048471. %F A036551 From _Colin Barker_, Aug 24 2016: (Start) %F A036551 a(n) = 9*a(n-1)-20*a(n-2)+12*a(n-3) for n>2. %F A036551 G.f.: (1-6*x+10*x^2) / ((1-x)*(1-2*x)*(1-6*x)). %F A036551 (End) %o A036551 (PARI) Vec((1-6*x+10*x^2)/((1-x)*(1-2*x)*(1-6*x)) + O(x^30)) \\ _Colin Barker_, Aug 24 2016 %Y A036551 Cf. A048471. %K A036551 nonn,easy %O A036551 0,2 %A A036551 _Clark Kimberling_ %E A036551 Simpler definition from _Ralf Stephan_, Feb 17 2004 %E A036551 Corrected by _T. D. Noe_, Nov 07 2006